Header file for real operations. More...

#include <math.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include "slu_Cnames.h"
#include "supermatrix.h"
#include "slu_util.h"

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Typedefs
typedef int	int_t

Functions
void	dgssv (superlu_options_t , SuperMatrix , int , int , SuperMatrix , SuperMatrix , SuperMatrix , SuperLUStat_t , int *)
	Driver routines. More...

void	dgssvx (superlu_options_t , SuperMatrix , int , int , int , char , double , double , SuperMatrix , SuperMatrix , void , int, SuperMatrix , SuperMatrix , double , double , double , double , GlobalLU_t , mem_usage_t , SuperLUStat_t , int *)

void	dgsisv (superlu_options_t , SuperMatrix , int , int , SuperMatrix , SuperMatrix , SuperMatrix , SuperLUStat_t , int *)

void	dgsisx (superlu_options_t , SuperMatrix , int , int , int , char , double , double , SuperMatrix , SuperMatrix , void , int, SuperMatrix , SuperMatrix , double , double , GlobalLU_t , mem_usage_t , SuperLUStat_t , int *)

void	dCreate_CompCol_Matrix (SuperMatrix , int, int, int, double , int , int , Stype_t, Dtype_t, Mtype_t)
	Supernodal LU factor related. More...

void	dCreate_CompRow_Matrix (SuperMatrix , int, int, int, double , int , int , Stype_t, Dtype_t, Mtype_t)

void	dCopy_CompCol_Matrix (SuperMatrix , SuperMatrix )
	Copy matrix A into matrix B. More...

void	dCreate_Dense_Matrix (SuperMatrix , int, int, double , int, Stype_t, Dtype_t, Mtype_t)

void	dCreate_SuperNode_Matrix (SuperMatrix , int, int, int, double , int , int , int , int , int *, Stype_t, Dtype_t, Mtype_t)

void	dCopy_Dense_Matrix (int, int, double , int, double , int)

void	countnz (const int, int , int , int , GlobalLU_t )
	Count the total number of nonzeros in factors L and U, and in the symmetrically reduced L. More...

void	ilu_countnz (const int, int , int , GlobalLU_t *)
	Count the total number of nonzeros in factors L and U. More...

void	fixupL (const int, const int , GlobalLU_t )
	Fix up the data storage lsub for L-subscripts. It removes the subscript sets for structural pruning, and applies permuation to the remaining subscripts. More...

void	dallocateA (int, int, double , int , int **)
	Allocate storage for original matrix A. More...

void	dgstrf (superlu_options_t , SuperMatrix , int, int, int , void , int, int , int , SuperMatrix , SuperMatrix , GlobalLU_t , SuperLUStat_t , int *)

int	dsnode_dfs (const int, const int, const int , const int , const int , int , int , GlobalLU_t )

int	dsnode_bmod (const int, const int, const int, double , double , GlobalLU_t , SuperLUStat_t )
	Performs numeric block updates within the relaxed snode. More...

void	dpanel_dfs (const int, const int, const int, SuperMatrix , int , int , double , int , int , int , int , int , int , int , GlobalLU_t )

void	dpanel_bmod (const int, const int, const int, const int, double , double , int , int , GlobalLU_t , SuperLUStat_t )

int	dcolumn_dfs (const int, const int, int , int , int , int , int , int , int , int , int , GlobalLU_t )

int	dcolumn_bmod (const int, const int, double , double , int , int , int, GlobalLU_t , SuperLUStat_t )

int	dcopy_to_ucol (int, int, int , int , int , double , GlobalLU_t *)

int	dpivotL (const int, const double, int , int , int , int , int , GlobalLU_t , SuperLUStat_t *)

void	dpruneL (const int, const int , const int, const int, const int , const int , int , GlobalLU_t *)

void	dreadmt (int , int , int , double , int , int *)

void	dGenXtrue (int, int, double *, int)

void	dFillRHS (trans_t, int, double , int, SuperMatrix , SuperMatrix *)
	Let rhs[i] = sum of i-th row of A, so the solution vector is all 1's. More...

void	dgstrs (trans_t, SuperMatrix , SuperMatrix , int , int , SuperMatrix , SuperLUStat_t , int *)

void	dgsitrf (superlu_options_t , SuperMatrix , int, int, int , void , int, int , int , SuperMatrix , SuperMatrix , GlobalLU_t , SuperLUStat_t , int *)

int	dldperm (int, int, int, int[], int[], double[], int[], double[], double[])

int	ilu_dsnode_dfs (const int, const int, const int , const int , const int , int , GlobalLU_t *)

void	ilu_dpanel_dfs (const int, const int, const int, SuperMatrix , int , int , double , double , int , int , int , int , int , int , GlobalLU_t )

int	ilu_dcolumn_dfs (const int, const int, int , int , int , int , int , int , int , int , GlobalLU_t *)

int	ilu_dcopy_to_ucol (int, int, int , int , int , double , int, milu_t, double, int, double , int , GlobalLU_t , double )

int	ilu_dpivotL (const int, const double, int , int , int, int , int , int , int , double, milu_t, double, GlobalLU_t , SuperLUStat_t )

int	ilu_ddrop_row (superlu_options_t , int, int, double, int, int , double , GlobalLU_t , double , double , int)

void	dgsequ (SuperMatrix , double , double , double , double , double , int *)
	Driver related. More...

void	dlaqgs (SuperMatrix , double , double , double, double, double, char )

void	dgscon (char , SuperMatrix , SuperMatrix , double, double , SuperLUStat_t , int )

double	dPivotGrowth (int, SuperMatrix , int , SuperMatrix , SuperMatrix )

void	dgsrfs (trans_t, SuperMatrix , SuperMatrix , SuperMatrix , int , int , char , double , double , SuperMatrix , SuperMatrix , double , double , SuperLUStat_t , int )

int	sp_dtrsv (char , char , char , SuperMatrix , SuperMatrix , double , SuperLUStat_t , int )
	Solves one of the systems of equations Ax = b, or A'x = b. More...

int	sp_dgemv (char , double, SuperMatrix , double , int, double, double , int)
	Performs one of the matrix-vector operations y := alphaAx + betay, or y := alphaA'x + betay,. More...

int	sp_dgemm (char , char , int, int, int, double, SuperMatrix , double , int, double, double *, int)

double	dmach (char *)

int	dLUMemInit (fact_t, void , int, int, int, int, int, double, SuperMatrix , SuperMatrix , GlobalLU_t , int , double )
	Memory-related. More...

void	dSetRWork (int, int, double , double , double *)
	Set up pointers for real working arrays. More...

void	dLUWorkFree (int , double , GlobalLU_t *)
	Free the working storage used by factor routines. More...

int	dLUMemXpand (int, int, MemType, int , GlobalLU_t )
	Expand the data structures for L and U during the factorization. More...

double *	doubleMalloc (int)

double *	doubleCalloc (int)

int	dmemory_usage (const int, const int, const int, const int)

int	dQuerySpace (SuperMatrix , SuperMatrix , mem_usage_t *)

int	ilu_dQuerySpace (SuperMatrix , SuperMatrix , mem_usage_t *)

void	dreadhb (FILE , int , int , int , double , int , int **)
	Auxiliary routines. More...

void	dreadrb (int , int , int , double , int , int *)

void	dreadtriple (int , int , int , double , int , int *)

void	dCompRow_to_CompCol (int, int, int, double , int , int , double , int , int *)
	Convert a row compressed storage into a column compressed storage. More...

void	dfill (double *, int, double)
	Fills a double precision array with a given value. More...

void	dinf_norm_error (int, SuperMatrix , double )
	Check the inf-norm of the error vector. More...

double	dqselect (int, double *, int)

void	dPrint_CompCol_Matrix (char , SuperMatrix )
	Routines for debugging. More...

void	dPrint_SuperNode_Matrix (char , SuperMatrix )

void	dPrint_Dense_Matrix (char , SuperMatrix )

void	dprint_lu_col (char , int, int, int , GlobalLU_t *)
	Diagnostic print of column "jcol" in the U/L factor. More...

int	print_double_vec (char , int, double )

void	dcheck_tempv (int, double *)
	Check whether tempv[] == 0. This should be true before and after calling any numeric routines, i.e., "panel_bmod" and "column_bmod". More...

int	dgemm_ (const char , const char , const int , const int , const int , const double , const double , const int , const double , const int , const double , double , const int *)
	BLAS. More...

int	dtrsv_ (char , char , char , int , double , int , double , int )

int	dtrsm_ (char , char , char , char , int , int , double , double , int , double , int *)

int	dgemv_ (char , int , int , double , double a, int , double , int , double , double , int *)

Detailed Description

The source code is distributed under BSD license, see the file License.txt at the top-level directory.

 
– SuperLU routine (version 4.1) –
Univ. of California Berkeley, Xerox Palo Alto Research Center,
and Lawrence Berkeley National Lab.
November, 2010

Global data structures used in LU factorization -

  nsuper: #supernodes = nsuper + 1, numbered [0, nsuper].
  (xsup,supno): supno[i] is the supernode no to which i belongs;
     xsup(s) points to the beginning of the s-th supernode.
     e.g.   supno 0 1 2 2 3 3 3 4 4 4 4 4   (n=12)
             xsup 0 1 2 4 7 12
     Note: dfs will be performed on supernode rep. relative to the new 
           row pivoting ordering

  (xlsub,lsub): lsub[*] contains the compressed subscript of
     rectangular supernodes; xlsub[j] points to the starting
     location of the j-th column in lsub[*]. Note that xlsub 
     is indexed by column.
     Storage: original row subscripts

     During the course of sparse LU factorization, we also use
     (xlsub,lsub) for the purpose of symmetric pruning. For each
     supernode {s,s+1,...,t=s+r} with first column s and last
     column t, the subscript set
        lsub[j], j=xlsub[s], .., xlsub[s+1]-1
     is the structure of column s (i.e. structure of this supernode).
     It is used for the storage of numerical values.
     Furthermore,
        lsub[j], j=xlsub[t], .., xlsub[t+1]-1
     is the structure of the last column t of this supernode.
     It is for the purpose of symmetric pruning. Therefore, the
     structural subscripts can be rearranged without making physical
     interchanges among the numerical values.

     However, if the supernode has only one column, then we
     only keep one set of subscripts. For any subscript interchange
     performed, similar interchange must be done on the numerical
     values.

     The last column structures (for pruning) will be removed
     after the numercial LU factorization phase.

  (xlusup,lusup): lusup[*] contains the numerical values of the
     rectangular supernodes; xlusup[j] points to the starting
     location of the j-th column in storage vector lusup[*]
     Note: xlusup is indexed by column.
     Each rectangular supernode is stored by column-major
     scheme, consistent with Fortran 2-dim array storage.

  (xusub,ucol,usub): ucol[*] stores the numerical values of
     U-columns outside the rectangular supernodes. The row
     subscript of nonzero ucol[k] is stored in usub[k].
     xusub[i] points to the starting location of column i in ucol.
     Storage: new row subscripts; that is subscripts of PA.

Typedef Documentation

typedef int int_t

Function Documentation

void countnz	(	const int	,
		int *	,
		int *	,
		int *	,
		GlobalLU_t *
	)

void dallocateA	(	int	,
		int	,
		double **	,
		int **	,
		int **
	)

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void dcheck_tempv	(	int	,
		double *
	)

int dcolumn_bmod	(	const int	jcol,
		const int	nseg,
		double *	dense,
		double *	tempv,
		int *	segrep,
		int *	repfnz,
		int	fpanelc,
		GlobalLU_t *	Glu,
		SuperLUStat_t *	stat
	)

Purpose:

Performs numeric block updates (sup-col) in topological order.
It features: col-col, 2cols-col, 3cols-col, and sup-col updates.
Special processing on the supernodal portion of L[*,j]
Return value:   0 - successful return
              > 0 - number of bytes allocated when run out of space

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int dcolumn_dfs	(	const int	m,
		const int	jcol,
		int *	perm_r,
		int *	nseg,
		int *	lsub_col,
		int *	segrep,
		int *	repfnz,
		int *	xprune,
		int *	marker,
		int *	parent,
		int *	xplore,
		GlobalLU_t *	Glu
	)

Purpose

  DCOLUMN_DFS performs a symbolic factorization on column jcol, and
  decide the supernode boundary.

  This routine does not use numeric values, but only use the RHS 
  row indices to start the dfs.

  A supernode representative is the last column of a supernode.
  The nonzeros in U[*,j] are segments that end at supernodal
  representatives. The routine returns a list of such supernodal 
  representatives in topological order of the dfs that generates them.
  The location of the first nonzero in each such supernodal segment
  (supernodal entry location) is also returned.

Local parameters

  nseg: no of segments in current U[*,j]
  jsuper: jsuper=EMPTY if column j does not belong to the same
     supernode as j-1. Otherwise, jsuper=nsuper.

  marker2: A-row –> A-row/col (0/1)
  repfnz: SuperA-col –> PA-row
  parent: SuperA-col –> SuperA-col
  xplore: SuperA-col –> index to L-structure

Return value

0 success;

0 number of bytes allocated when run out of space.

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void dCompRow_to_CompCol	(	int	,
		int	,
		int	,
		double *	,
		int *	,
		int *	,
		double **	,
		int **	,
		int **
	)

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void dCopy_CompCol_Matrix	(	SuperMatrix *	,
		SuperMatrix *
	)

void dCopy_Dense_Matrix	(	int	,
		int	,
		double *	,
		int	,
		double *	,
		int
	)

Copies a two-dimensional matrix X to another matrix Y.

int dcopy_to_ucol	(	int	,
		int	,
		int *	,
		int *	,
		int *	,
		double *	,
		GlobalLU_t *
	)

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void dCreate_CompCol_Matrix	(	SuperMatrix *	,
		int	,
		int	,
		int	,
		double *	,
		int *	,
		int *	,
		Stype_t	,
		Dtype_t	,
		Mtype_t
	)

void dCreate_CompRow_Matrix	(	SuperMatrix *	,
		int	,
		int	,
		int	,
		double *	,
		int *	,
		int *	,
		Stype_t	,
		Dtype_t	,
		Mtype_t
	)

void dCreate_Dense_Matrix	(	SuperMatrix *	,
		int	,
		int	,
		double *	,
		int	,
		Stype_t	,
		Dtype_t	,
		Mtype_t
	)

void dCreate_SuperNode_Matrix	(	SuperMatrix *	,
		int	,
		int	,
		int	,
		double *	,
		int *	,
		int *	,
		int *	,
		int *	,
		int *	,
		Stype_t	,
		Dtype_t	,
		Mtype_t
	)

void dfill	(	double *	,
		int	,
		double
	)

void dFillRHS	(	trans_t	,
		int	,
		double *	,
		int	,
		SuperMatrix *	,
		SuperMatrix *
	)

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int dgemm_	(	const char *	,
		const char *	,
		const int *	,
		const int *	,
		const int *	,
		const double *	,
		const double *	,
		const int *	,
		const double *	,
		const int *	,
		const double *	,
		double *	,
		const int *
	)

int dgemv_	(	char *	,
		int *	,
		int *	,
		double *	,
		double *	a,
		int *	,
		double *	,
		int *	,
		double *	,
		double *	,
		int *
	)

void dGenXtrue	(	int	,
		int	,
		double *	,
		int
	)

void dgscon	(	char *	norm,
		SuperMatrix *	L,
		SuperMatrix *	U,
		double	anorm,
		double *	rcond,
		SuperLUStat_t *	stat,
		int *	info
	)

Purpose

  DGSCON estimates the reciprocal of the condition number of a general 
  real matrix A, in either the 1-norm or the infinity-norm, using   
  the LU factorization computed by DGETRF.   *

  An estimate is obtained for norm(inv(A)), and the reciprocal of the   
  condition number is computed as   
     RCOND = 1 / ( norm(A) * norm(inv(A)) ).

  See supermatrix.h for the definition of 'SuperMatrix' structure.

Arguments

   NORM    (input) char*
           Specifies whether the 1-norm condition number or the   
           infinity-norm condition number is required:   
           = '1' or 'O':  1-norm;   
           = 'I':         Infinity-norm.

   L       (input) SuperMatrix*
           The factor L from the factorization Pr*A*Pc=L*U as computed by
           dgstrf(). Use compressed row subscripts storage for supernodes,
           i.e., L has types: Stype = SLU_SC, Dtype = SLU_D, Mtype = SLU_TRLU.

   U       (input) SuperMatrix*
           The factor U from the factorization Pr*A*Pc=L*U as computed by
           dgstrf(). Use column-wise storage scheme, i.e., U has types:
           Stype = SLU_NC, Dtype = SLU_D, Mtype = SLU_TRU.

   ANORM   (input) double
           If NORM = '1' or 'O', the 1-norm of the original matrix A.   
           If NORM = 'I', the infinity-norm of the original matrix A.

   RCOND   (output) double*
          The reciprocal of the condition number of the matrix A,   
          computed as RCOND = 1/(norm(A) * norm(inv(A))).

   INFO    (output) int*
          = 0:  successful exit   
          < 0:  if INFO = -i, the i-th argument had an illegal value

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void dgsequ	(	SuperMatrix *	A,
		double *	r,
		double *	c,
		double *	rowcnd,
		double *	colcnd,
		double *	amax,
		int *	info
	)

Purpose

  DGSEQU computes row and column scalings intended to equilibrate an   
  M-by-N sparse matrix A and reduce its condition number. R returns the row
  scale factors and C the column scale factors, chosen to try to make   
  the largest element in each row and column of the matrix B with   
  elements B(i,j)=R(i)*A(i,j)*C(j) have absolute value 1.

  R(i) and C(j) are restricted to be between SMLNUM = smallest safe   
  number and BIGNUM = largest safe number.  Use of these scaling   
  factors is not guaranteed to reduce the condition number of A but   
  works well in practice.

  See supermatrix.h for the definition of 'SuperMatrix' structure.

Arguments

  A       (input) SuperMatrix*
          The matrix of dimension (A->nrow, A->ncol) whose equilibration
          factors are to be computed. The type of A can be:
          Stype = SLU_NC; Dtype = SLU_D; Mtype = SLU_GE.

  R       (output) double*, size A->nrow
          If INFO = 0 or INFO > M, R contains the row scale factors   
          for A.

  C       (output) double*, size A->ncol
          If INFO = 0,  C contains the column scale factors for A.

  ROWCND  (output) double*
          If INFO = 0 or INFO > M, ROWCND contains the ratio of the   
          smallest R(i) to the largest R(i).  If ROWCND >= 0.1 and   
          AMAX is neither too large nor too small, it is not worth   
          scaling by R.

  COLCND  (output) double*
          If INFO = 0, COLCND contains the ratio of the smallest   
          C(i) to the largest C(i).  If COLCND >= 0.1, it is not   
          worth scaling by C.

  AMAX    (output) double*
          Absolute value of largest matrix element.  If AMAX is very   
          close to overflow or very close to underflow, the matrix   
          should be scaled.

  INFO    (output) int*
          = 0:  successful exit   
          < 0:  if INFO = -i, the i-th argument had an illegal value   
          > 0:  if INFO = i,  and i is   
                <= A->nrow:  the i-th row of A is exactly zero   
                >  A->ncol:  the (i-M)-th column of A is exactly zero

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void dgsisv	(	superlu_options_t *	,
		SuperMatrix *	,
		int *	,
		int *	,
		SuperMatrix *	,
		SuperMatrix *	,
		SuperMatrix *	,
		SuperLUStat_t *	,
		int *
	)

void dgsisx	(	superlu_options_t *	options,
		SuperMatrix *	A,
		int *	perm_c,
		int *	perm_r,
		int *	etree,
		char *	equed,
		double *	R,
		double *	C,
		SuperMatrix *	L,
		SuperMatrix *	U,
		void *	work,
		int	lwork,
		SuperMatrix *	B,
		SuperMatrix *	X,
		double *	recip_pivot_growth,
		double *	rcond,
		GlobalLU_t *	Glu,
		mem_usage_t *	mem_usage,
		SuperLUStat_t *	stat,
		int *	info
	)

Purpose

DGSISX computes an approximate solutions of linear equations
A*X=B or A'*X=B, using the ILU factorization from dgsitrf().
An estimation of the condition number is provided. 
The routine performs the following steps:

  1. If A is stored column-wise (A->Stype = SLU_NC):

     1.1. If options->Equil = YES or options->RowPerm = LargeDiag, scaling
          factors are computed to equilibrate the system:
          options->Trans = NOTRANS:
         diag(R)*A*diag(C) *inv(diag(C))*X = diag(R)*B
          options->Trans = TRANS:
         (diag(R)*A*diag(C))**T *inv(diag(R))*X = diag(C)*B
          options->Trans = CONJ:
         (diag(R)*A*diag(C))**H *inv(diag(R))*X = diag(C)*B
          Whether or not the system will be equilibrated depends on the
          scaling of the matrix A, but if equilibration is used, A is
          overwritten by diag(R)*A*diag(C) and B by diag(R)*B
          (if options->Trans=NOTRANS) or diag(C)*B (if options->Trans
          = TRANS or CONJ).

     1.2. Permute columns of A, forming A*Pc, where Pc is a permutation
          matrix that usually preserves sparsity.
          For more details of this step, see sp_preorder.c.

     1.3. If options->Fact != FACTORED, the LU decomposition is used to
          factor the matrix A (after equilibration if options->Equil = YES)
          as Pr*A*Pc = L*U, with Pr determined by partial pivoting.

     1.4. Compute the reciprocal pivot growth factor.

     1.5. If some U(i,i) = 0, so that U is exactly singular, then the
          routine fills a small number on the diagonal entry, that is
        U(i,i) = ||A(:,i)||_oo * options->ILU_FillTol ** (1 - i / n),
          and info will be increased by 1. The factored form of A is used
          to estimate the condition number of the preconditioner. If the
          reciprocal of the condition number is less than machine precision,
          info = A->ncol+1 is returned as a warning, but the routine still
          goes on to solve for X.

     1.6. The system of equations is solved for X using the factored form
          of A.

     1.7. options->IterRefine is not used

     1.8. If equilibration was used, the matrix X is premultiplied by
          diag(C) (if options->Trans = NOTRANS) or diag(R)
          (if options->Trans = TRANS or CONJ) so that it solves the
          original system before equilibration.

     1.9. options for ILU only
          1) If options->RowPerm = LargeDiag, MC64 is used to scale and
        permute the matrix to an I-matrix, that is Pr*Dr*A*Dc has
        entries of modulus 1 on the diagonal and off-diagonal entries
        of modulus at most 1. If MC64 fails, dgsequ() is used to
        equilibrate the system.
             ( Default: LargeDiag )
          2) options->ILU_DropTol = tau is the threshold for dropping.
        For L, it is used directly (for the whole row in a supernode);
        For U, ||A(:,i)||_oo * tau is used as the threshold
             for the    i-th column.
        If a secondary dropping rule is required, tau will
             also be used to compute the second threshold.
             ( Default: 1e-4 )
          3) options->ILU_FillFactor = gamma, used as the initial guess
        of memory growth.
        If a secondary dropping rule is required, it will also
             be used as an upper bound of the memory.
             ( Default: 10 )
          4) options->ILU_DropRule specifies the dropping rule.
        Option        Meaning
        ======        ===========
        DROP_BASIC:   Basic dropping rule, supernodal based ILUTP(tau).
        DROP_PROWS:   Supernodal based ILUTP(p,tau), p = gamma*nnz(A)/n.
        DROP_COLUMN:  Variant of ILUTP(p,tau), for j-th column,
                      p = gamma * nnz(A(:,j)).
        DROP_AREA:    Variation of ILUTP, for j-th column, use
                      nnz(F(:,1:j)) / nnz(A(:,1:j)) to control memory.
        DROP_DYNAMIC: Modify the threshold tau during factorizaion:
                      If nnz(L(:,1:j)) / nnz(A(:,1:j)) > gamma
                          tau_L(j) := MIN(tau_0, tau_L(j-1) * 2);
                      Otherwise
                          tau_L(j) := MAX(tau_0, tau_L(j-1) / 2);
                      tau_U(j) uses the similar rule.
                      NOTE: the thresholds used by L and U are separate.
        DROP_INTERP:  Compute the second dropping threshold by
                      interpolation instead of sorting (default).
                      In this case, the actual fill ratio is not
                      guaranteed smaller than gamma.
        DROP_PROWS, DROP_COLUMN and DROP_AREA are mutually exclusive.
        ( Default: DROP_BASIC | DROP_AREA )
          5) options->ILU_Norm is the criterion of measuring the magnitude
        of a row in a supernode of L. ( Default is INF_NORM )
        options->ILU_Norm       RowSize(x[1:n])
        =================       ===============
        ONE_NORM                ||x||_1 / n
        TWO_NORM                ||x||_2 / sqrt(n)
        INF_NORM                max{|x[i]|}
          6) options->ILU_MILU specifies the type of MILU's variation.
        = SILU: do not perform Modified ILU;
        = SMILU_1 (not recommended):
            U(i,i) := U(i,i) + sum(dropped entries);
        = SMILU_2:
            U(i,i) := U(i,i) + SGN(U(i,i)) * sum(dropped entries);
        = SMILU_3:
            U(i,i) := U(i,i) + SGN(U(i,i)) * sum(|dropped entries|);
        NOTE: Even SMILU_1 does not preserve the column sum because of
        late dropping.
             ( Default: SILU )
          7) options->ILU_FillTol is used as the perturbation when
        encountering zero pivots. If some U(i,i) = 0, so that U is
        exactly singular, then
           U(i,i) := ||A(:,i)|| * options->ILU_FillTol ** (1 - i / n).
             ( Default: 1e-2 )

  2. If A is stored row-wise (A->Stype = SLU_NR), apply the above algorithm
     to the transpose of A:

     2.1. If options->Equil = YES or options->RowPerm = LargeDiag, scaling
          factors are computed to equilibrate the system:
          options->Trans = NOTRANS:
         diag(R)*A*diag(C) *inv(diag(C))*X = diag(R)*B
          options->Trans = TRANS:
         (diag(R)*A*diag(C))**T *inv(diag(R))*X = diag(C)*B
          options->Trans = CONJ:
         (diag(R)*A*diag(C))**H *inv(diag(R))*X = diag(C)*B
          Whether or not the system will be equilibrated depends on the
          scaling of the matrix A, but if equilibration is used, A' is
          overwritten by diag(R)*A'*diag(C) and B by diag(R)*B
          (if trans='N') or diag(C)*B (if trans = 'T' or 'C').

     2.2. Permute columns of transpose(A) (rows of A),
          forming transpose(A)*Pc, where Pc is a permutation matrix that
          usually preserves sparsity.
          For more details of this step, see sp_preorder.c.

     2.3. If options->Fact != FACTORED, the LU decomposition is used to
          factor the transpose(A) (after equilibration if
          options->Fact = YES) as Pr*transpose(A)*Pc = L*U with the
          permutation Pr determined by partial pivoting.

     2.4. Compute the reciprocal pivot growth factor.

     2.5. If some U(i,i) = 0, so that U is exactly singular, then the
          routine fills a small number on the diagonal entry, that is
         U(i,i) = ||A(:,i)||_oo * options->ILU_FillTol ** (1 - i / n).
          And info will be increased by 1. The factored form of A is used
          to estimate the condition number of the preconditioner. If the
          reciprocal of the condition number is less than machine precision,
          info = A->ncol+1 is returned as a warning, but the routine still
          goes on to solve for X.

     2.6. The system of equations is solved for X using the factored form
          of transpose(A).

     2.7. If options->IterRefine is not used.

     2.8. If equilibration was used, the matrix X is premultiplied by
          diag(C) (if options->Trans = NOTRANS) or diag(R)
          (if options->Trans = TRANS or CONJ) so that it solves the
          original system before equilibration.

  See supermatrix.h for the definition of 'SuperMatrix' structure.

Arguments

options (input) superlu_options_t*
        The structure defines the input parameters to control
        how the LU decomposition will be performed and how the
        system will be solved.

A          (input/output) SuperMatrix*
        Matrix A in A*X=B, of dimension (A->nrow, A->ncol). The number
        of the linear equations is A->nrow. Currently, the type of A can be:
        Stype = SLU_NC or SLU_NR, Dtype = SLU_D, Mtype = SLU_GE.
        In the future, more general A may be handled.

        On entry, If options->Fact = FACTORED and equed is not 'N',
        then A must have been equilibrated by the scaling factors in
        R and/or C.
        On exit, A is not modified
        if options->Equil = NO, or
        if options->Equil = YES but equed = 'N' on exit, or
        if options->RowPerm = NO.

        Otherwise, if options->Equil = YES and equed is not 'N',
        A is scaled as follows:
        If A->Stype = SLU_NC:
          equed = 'R':  A := diag(R) * A
          equed = 'C':  A := A * diag(C)
          equed = 'B':  A := diag(R) * A * diag(C).
        If A->Stype = SLU_NR:
          equed = 'R':  transpose(A) := diag(R) * transpose(A)
          equed = 'C':  transpose(A) := transpose(A) * diag(C)
          equed = 'B':  transpose(A) := diag(R) * transpose(A) * diag(C).

        If options->RowPerm = LargeDiag, MC64 is used to scale and permute
           the matrix to an I-matrix, that is A is modified as follows:
           P*Dr*A*Dc has entries of modulus 1 on the diagonal and 
           off-diagonal entries of modulus at most 1. P is a permutation
           obtained from MC64.
           If MC64 fails, dgsequ() is used to equilibrate the system,
           and A is scaled as above, but no permutation is involved.
           On exit, A is restored to the orginal row numbering, so
           Dr*A*Dc is returned.

perm_c  (input/output) int*
        If A->Stype = SLU_NC, Column permutation vector of size A->ncol,
        which defines the permutation matrix Pc; perm_c[i] = j means
        column i of A is in position j in A*Pc.
        On exit, perm_c may be overwritten by the product of the input
        perm_c and a permutation that postorders the elimination tree
        of Pc'*A'*A*Pc; perm_c is not changed if the elimination tree
        is already in postorder.

        If A->Stype = SLU_NR, column permutation vector of size A->nrow,
        which describes permutation of columns of transpose(A) 
        (rows of A) as described above.

perm_r  (input/output) int*
        If A->Stype = SLU_NC, row permutation vector of size A->nrow, 
        which defines the permutation matrix Pr, and is determined
        by MC64 first then followed by partial pivoting.
        perm_r[i] = j means row i of A is in position j in Pr*A.

        If A->Stype = SLU_NR, permutation vector of size A->ncol, which
        determines permutation of rows of transpose(A)
        (columns of A) as described above.

        If options->Fact = SamePattern_SameRowPerm, the pivoting routine
        will try to use the input perm_r, unless a certain threshold
        criterion is violated. In that case, perm_r is overwritten by a
        new permutation determined by partial pivoting or diagonal
        threshold pivoting.
        Otherwise, perm_r is output argument.

etree   (input/output) int*,  dimension (A->ncol)
        Elimination tree of Pc'*A'*A*Pc.
        If options->Fact != FACTORED and options->Fact != DOFACT,
        etree is an input argument, otherwise it is an output argument.
        Note: etree is a vector of parent pointers for a forest whose
        vertices are the integers 0 to A->ncol-1; etree[root]==A->ncol.

equed   (input/output) char*
        Specifies the form of equilibration that was done.
        = 'N': No equilibration.
        = 'R': Row equilibration, i.e., A was premultiplied by diag(R).
        = 'C': Column equilibration, i.e., A was postmultiplied by diag(C).
        = 'B': Both row and column equilibration, i.e., A was replaced 
          by diag(R)*A*diag(C).
        If options->Fact = FACTORED, equed is an input argument,
        otherwise it is an output argument.

R          (input/output) double*, dimension (A->nrow)
        The row scale factors for A or transpose(A).
        If equed = 'R' or 'B', A (if A->Stype = SLU_NC) or transpose(A)
            (if A->Stype = SLU_NR) is multiplied on the left by diag(R).
        If equed = 'N' or 'C', R is not accessed.
        If options->Fact = FACTORED, R is an input argument,
            otherwise, R is output.
        If options->Fact = FACTORED and equed = 'R' or 'B', each element
            of R must be positive.

C          (input/output) double*, dimension (A->ncol)
        The column scale factors for A or transpose(A).
        If equed = 'C' or 'B', A (if A->Stype = SLU_NC) or transpose(A)
            (if A->Stype = SLU_NR) is multiplied on the right by diag(C).
        If equed = 'N' or 'R', C is not accessed.
        If options->Fact = FACTORED, C is an input argument,
            otherwise, C is output.
        If options->Fact = FACTORED and equed = 'C' or 'B', each element
            of C must be positive.

L          (output) SuperMatrix*
        The factor L from the factorization
            Pr*A*Pc=L*U         (if A->Stype SLU_= NC) or
            Pr*transpose(A)*Pc=L*U      (if A->Stype = SLU_NR).
        Uses compressed row subscripts storage for supernodes, i.e.,
        L has types: Stype = SLU_SC, Dtype = SLU_D, Mtype = SLU_TRLU.

U          (output) SuperMatrix*
        The factor U from the factorization
            Pr*A*Pc=L*U         (if A->Stype = SLU_NC) or
            Pr*transpose(A)*Pc=L*U      (if A->Stype = SLU_NR).
        Uses column-wise storage scheme, i.e., U has types:
        Stype = SLU_NC, Dtype = SLU_D, Mtype = SLU_TRU.

work    (workspace/output) void*, size (lwork) (in bytes)
        User supplied workspace, should be large enough
        to hold data structures for factors L and U.
        On exit, if fact is not 'F', L and U point to this array.

lwork   (input) int
        Specifies the size of work array in bytes.
        = 0:  allocate space internally by system malloc;
        > 0:  use user-supplied work array of length lwork in bytes,
         returns error if space runs out.
        = -1: the routine guesses the amount of space needed without
         performing the factorization, and returns it in
         mem_usage->total_needed; no other side effects.

        See argument 'mem_usage' for memory usage statistics.

B          (input/output) SuperMatrix*
        B has types: Stype = SLU_DN, Dtype = SLU_D, Mtype = SLU_GE.
        On entry, the right hand side matrix.
        If B->ncol = 0, only LU decomposition is performed, the triangular
                   solve is skipped.
        On exit,
           if equed = 'N', B is not modified; otherwise
           if A->Stype = SLU_NC:
         if options->Trans = NOTRANS and equed = 'R' or 'B',
            B is overwritten by diag(R)*B;
         if options->Trans = TRANS or CONJ and equed = 'C' of 'B',
            B is overwritten by diag(C)*B;
           if A->Stype = SLU_NR:
         if options->Trans = NOTRANS and equed = 'C' or 'B',
            B is overwritten by diag(C)*B;
         if options->Trans = TRANS or CONJ and equed = 'R' of 'B',
            B is overwritten by diag(R)*B.

X          (output) SuperMatrix*
        X has types: Stype = SLU_DN, Dtype = SLU_D, Mtype = SLU_GE.
        If info = 0 or info = A->ncol+1, X contains the solution matrix
        to the original system of equations. Note that A and B are modified
        on exit if equed is not 'N', and the solution to the equilibrated
        system is inv(diag(C))*X if options->Trans = NOTRANS and
        equed = 'C' or 'B', or inv(diag(R))*X if options->Trans = 'T' or 'C'
        and equed = 'R' or 'B'.

recip_pivot_growth (output) double*
        The reciprocal pivot growth factor max_j( norm(A_j)/norm(U_j) ).
        The infinity norm is used. If recip_pivot_growth is much less
        than 1, the stability of the LU factorization could be poor.

rcond   (output) double*
        The estimate of the reciprocal condition number of the matrix A
        after equilibration (if done). If rcond is less than the machine
        precision (in particular, if rcond = 0), the matrix is singular
        to working precision. This condition is indicated by a return
        code of info > 0.

mem_usage (output) mem_usage_t* Record the memory usage statistics, consisting of following fields:

for_lu (float) The amount of space used in bytes for L data structures.
total_needed (float) The amount of space needed in bytes to perform factorization.
expansions (int) The number of memory expansions during the LU factorization.

stat   (output) SuperLUStat_t*
       Record the statistics on runtime and floating-point operation count.
       See slu_util.h for the definition of 'SuperLUStat_t'.

info    (output) int*
        = 0: successful exit
        < 0: if info = -i, the i-th argument had an illegal value
        > 0: if info = i, and i is
        <= A->ncol: number of zero pivots. They are replaced by small
              entries due to options->ILU_FillTol.
        = A->ncol+1: U is nonsingular, but RCOND is less than machine
              precision, meaning that the matrix is singular to
              working precision. Nevertheless, the solution and
              error bounds are computed because there are a number
              of situations where the computed solution can be more
              accurate than the value of RCOND would suggest.
        > A->ncol+1: number of bytes allocated when memory allocation
              failure occurred, plus A->ncol.

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void dgsitrf	(	superlu_options_t *	options,
		SuperMatrix *	A,
		int	relax,
		int	panel_size,
		int *	etree,
		void *	work,
		int	lwork,
		int *	perm_c,
		int *	perm_r,
		SuperMatrix *	L,
		SuperMatrix *	U,
		GlobalLU_t *	Glu,
		SuperLUStat_t *	stat,
		int *	info
	)

Purpose

DGSITRF computes an ILU factorization of a general sparse m-by-n
matrix A using partial pivoting with row interchanges.
The factorization has the form
    Pr * A = L * U
where Pr is a row permutation matrix, L is lower triangular with unit
diagonal elements (lower trapezoidal if A->nrow > A->ncol), and U is upper
triangular (upper trapezoidal if A->nrow < A->ncol).

See supermatrix.h for the definition of 'SuperMatrix' structure.

Arguments

options (input) superlu_options_t*
        The structure defines the input parameters to control
        how the ILU decomposition will be performed.

A           (input) SuperMatrix*
         Original matrix A, permuted by columns, of dimension
         (A->nrow, A->ncol). The type of A can be:
         Stype = SLU_NCP; Dtype = SLU_D; Mtype = SLU_GE.

relax    (input) int
         To control degree of relaxing supernodes. If the number
         of nodes (columns) in a subtree of the elimination tree is less
         than relax, this subtree is considered as one supernode,
         regardless of the row structures of those columns.

panel_size (input) int
         A panel consists of at most panel_size consecutive columns.

etree    (input) int*, dimension (A->ncol)
         Elimination tree of A'*A.
         Note: etree is a vector of parent pointers for a forest whose
         vertices are the integers 0 to A->ncol-1; etree[root]==A->ncol.
         On input, the columns of A should be permuted so that the
         etree is in a certain postorder.

work     (input/output) void*, size (lwork) (in bytes)
         User-supplied work space and space for the output data structures.
         Not referenced if lwork = 0;

lwork   (input) int
        Specifies the size of work array in bytes.
        = 0:  allocate space internally by system malloc;
        > 0:  use user-supplied work array of length lwork in bytes,
         returns error if space runs out.
        = -1: the routine guesses the amount of space needed without
         performing the factorization, and returns it in
         *info; no other side effects.

perm_c   (input) int*, dimension (A->ncol)
         Column permutation vector, which defines the
         permutation matrix Pc; perm_c[i] = j means column i of A is
         in position j in A*Pc.
         When searching for diagonal, perm_c[*] is applied to the
         row subscripts of A, so that diagonal threshold pivoting
         can find the diagonal of A, rather than that of A*Pc.

perm_r   (input/output) int*, dimension (A->nrow)
         Row permutation vector which defines the permutation matrix Pr,
         perm_r[i] = j means row i of A is in position j in Pr*A.
         If options->Fact = SamePattern_SameRowPerm, the pivoting routine
            will try to use the input perm_r, unless a certain threshold
            criterion is violated. In that case, perm_r is overwritten by
            a new permutation determined by partial pivoting or diagonal
            threshold pivoting.
         Otherwise, perm_r is output argument;

L           (output) SuperMatrix*
         The factor L from the factorization Pr*A=L*U; use compressed row
         subscripts storage for supernodes, i.e., L has type:
         Stype = SLU_SC, Dtype = SLU_D, Mtype = SLU_TRLU.

U           (output) SuperMatrix*
         The factor U from the factorization Pr*A*Pc=L*U. Use column-wise
         storage scheme, i.e., U has types: Stype = SLU_NC,
         Dtype = SLU_D, Mtype = SLU_TRU.

Glu      (input/output) GlobalLU_t *
         If options->Fact == SamePattern_SameRowPerm, it is an input;
             The matrix A will be factorized assuming that a 
             factorization of a matrix with the same sparsity pattern
             and similar numerical values was performed prior to this one.
             Therefore, this factorization will reuse both row and column
        scaling factors R and C, both row and column permutation
        vectors perm_r and perm_c, and the L & U data structures
        set up from the previous factorization.
         Otherwise, it is an output.

stat     (output) SuperLUStat_t*
         Record the statistics on runtime and floating-point operation count.
         See slu_util.h for the definition of 'SuperLUStat_t'.

info     (output) int*
         = 0: successful exit
         < 0: if info = -i, the i-th argument had an illegal value
         > 0: if info = i, and i is
            <= A->ncol: number of zero pivots. They are replaced by small
          entries according to options->ILU_FillTol.
            > A->ncol: number of bytes allocated when memory allocation
          failure occurred, plus A->ncol. If lwork = -1, it is
          the estimated amount of space needed, plus A->ncol.

Local Working Arrays:

  m = number of rows in the matrix
  n = number of columns in the matrix

  marker[0:3*m-1]: marker[i] = j means that node i has been
     reached when working on column j.
     Storage: relative to original row subscripts
     NOTE: There are 4 of them:
           marker/marker1 are used for panel dfs, see (ilu_)dpanel_dfs.c;
           marker2 is used for inner-factorization, see (ilu)_dcolumn_dfs.c;
           marker_relax(has its own space) is used for relaxed supernodes.

  parent[0:m-1]: parent vector used during dfs
     Storage: relative to new row subscripts

  xplore[0:m-1]: xplore[i] gives the location of the next (dfs)
     unexplored neighbor of i in lsub[*]

  segrep[0:nseg-1]: contains the list of supernodal representatives
     in topological order of the dfs. A supernode representative is the
     last column of a supernode.
     The maximum size of segrep[] is n.

  repfnz[0:W*m-1]: for a nonzero segment U[*,j] that ends at a
     supernodal representative r, repfnz[r] is the location of the first
     nonzero in this segment.  It is also used during the dfs: repfnz[r]>0
     indicates the supernode r has been explored.
     NOTE: There are W of them, each used for one column of a panel.

  panel_lsub[0:W*m-1]: temporary for the nonzeros row indices below
     the panel diagonal. These are filled in during dpanel_dfs(), and are
     used later in the inner LU factorization within the panel.
     panel_lsub[]/dense[] pair forms the SPA data structure.
     NOTE: There are W of them.

  dense[0:W*m-1]: sparse accumulating (SPA) vector for intermediate values;
           NOTE: there are W of them.

  tempv[0:*]: real temporary used for dense numeric kernels;
     The size of this array is defined by NUM_TEMPV() in slu_util.h.
     It is also used by the dropping routine ilu_ddrop_row().

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void dgsrfs	(	trans_t	trans,
		SuperMatrix *	A,
		SuperMatrix *	L,
		SuperMatrix *	U,
		int *	perm_c,
		int *	perm_r,
		char *	equed,
		double *	R,
		double *	C,
		SuperMatrix *	B,
		SuperMatrix *	X,
		double *	ferr,
		double *	berr,
		SuperLUStat_t *	stat,
		int *	info
	)

Purpose

  DGSRFS improves the computed solution to a system of linear   
  equations and provides error bounds and backward error estimates for 
  the solution.

  If equilibration was performed, the system becomes:
          (diag(R)*A_original*diag(C)) * X = diag(R)*B_original.

  See supermatrix.h for the definition of 'SuperMatrix' structure.

Arguments

trans   (input) trans_t
         Specifies the form of the system of equations:
         = NOTRANS: A * X = B  (No transpose)
         = TRANS:   A'* X = B  (Transpose)
         = CONJ:    A**H * X = B  (Conjugate transpose)

  A       (input) SuperMatrix*
          The original matrix A in the system, or the scaled A if
          equilibration was done. The type of A can be:
          Stype = SLU_NC, Dtype = SLU_D, Mtype = SLU_GE.

  L       (input) SuperMatrix*
          The factor L from the factorization Pr*A*Pc=L*U. Use
          compressed row subscripts storage for supernodes, 
          i.e., L has types: Stype = SLU_SC, Dtype = SLU_D, Mtype = SLU_TRLU.

  U       (input) SuperMatrix*
          The factor U from the factorization Pr*A*Pc=L*U as computed by
          dgstrf(). Use column-wise storage scheme, 
          i.e., U has types: Stype = SLU_NC, Dtype = SLU_D, Mtype = SLU_TRU.

  perm_c  (input) int*, dimension (A->ncol)
          Column permutation vector, which defines the 
          permutation matrix Pc; perm_c[i] = j means column i of A is 
          in position j in A*Pc.

  perm_r  (input) int*, dimension (A->nrow)
          Row permutation vector, which defines the permutation matrix Pr;
          perm_r[i] = j means row i of A is in position j in Pr*A.

  equed   (input) Specifies the form of equilibration that was done.
          = 'N': No equilibration.
          = 'R': Row equilibration, i.e., A was premultiplied by diag(R).
          = 'C': Column equilibration, i.e., A was postmultiplied by
                 diag(C).
          = 'B': Both row and column equilibration, i.e., A was replaced 
                 by diag(R)*A*diag(C).

  R       (input) double*, dimension (A->nrow)
          The row scale factors for A.
          If equed = 'R' or 'B', A is premultiplied by diag(R).
          If equed = 'N' or 'C', R is not accessed.

  C       (input) double*, dimension (A->ncol)
          The column scale factors for A.
          If equed = 'C' or 'B', A is postmultiplied by diag(C).
          If equed = 'N' or 'R', C is not accessed.

  B       (input) SuperMatrix*
          B has types: Stype = SLU_DN, Dtype = SLU_D, Mtype = SLU_GE.
          The right hand side matrix B.
          if equed = 'R' or 'B', B is premultiplied by diag(R).

  X       (input/output) SuperMatrix*
          X has types: Stype = SLU_DN, Dtype = SLU_D, Mtype = SLU_GE.
          On entry, the solution matrix X, as computed by dgstrs().
          On exit, the improved solution matrix X.
          if *equed = 'C' or 'B', X should be premultiplied by diag(C)
              in order to obtain the solution to the original system.

  FERR    (output) double*, dimension (B->ncol)   
          The estimated forward error bound for each solution vector   
          X(j) (the j-th column of the solution matrix X).   
          If XTRUE is the true solution corresponding to X(j), FERR(j) 
          is an estimated upper bound for the magnitude of the largest 
          element in (X(j) - XTRUE) divided by the magnitude of the   
          largest element in X(j).  The estimate is as reliable as   
          the estimate for RCOND, and is almost always a slight   
          overestimate of the true error.

  BERR    (output) double*, dimension (B->ncol)   
          The componentwise relative backward error of each solution   
          vector X(j) (i.e., the smallest relative change in   
          any element of A or B that makes X(j) an exact solution).

  stat     (output) SuperLUStat_t*
           Record the statistics on runtime and floating-point operation count.
           See util.h for the definition of 'SuperLUStat_t'.

  info    (output) int*   
          = 0:  successful exit   
           < 0:  if INFO = -i, the i-th argument had an illegal value

Internal Parameters

   ITMAX is the maximum number of steps of iterative refinement.

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void dgssv	(	superlu_options_t *	options,
		SuperMatrix *	A,
		int *	perm_c,
		int *	perm_r,
		SuperMatrix *	L,
		SuperMatrix *	U,
		SuperMatrix *	B,
		SuperLUStat_t *	stat,
		int *	info
	)

Purpose

DGSSV solves the system of linear equations A*X=B, using the
LU factorization from DGSTRF. It performs the following steps:

  1. If A is stored column-wise (A->Stype = SLU_NC):

     1.1. Permute the columns of A, forming A*Pc, where Pc
          is a permutation matrix. For more details of this step, 
          see sp_preorder.c.

     1.2. Factor A as Pr*A*Pc=L*U with the permutation Pr determined
          by Gaussian elimination with partial pivoting.
          L is unit lower triangular with offdiagonal entries
          bounded by 1 in magnitude, and U is upper triangular.

     1.3. Solve the system of equations A*X=B using the factored
          form of A.

  2. If A is stored row-wise (A->Stype = SLU_NR), apply the
     above algorithm to the transpose of A:

     2.1. Permute columns of transpose(A) (rows of A),
          forming transpose(A)*Pc, where Pc is a permutation matrix. 
          For more details of this step, see sp_preorder.c.

     2.2. Factor A as Pr*transpose(A)*Pc=L*U with the permutation Pr
          determined by Gaussian elimination with partial pivoting.
          L is unit lower triangular with offdiagonal entries
          bounded by 1 in magnitude, and U is upper triangular.

     2.3. Solve the system of equations A*X=B using the factored
          form of A.

  See supermatrix.h for the definition of 'SuperMatrix' structure.

Arguments

options (input) superlu_options_t*
        The structure defines the input parameters to control
        how the LU decomposition will be performed and how the
        system will be solved.

A       (input) SuperMatrix*
        Matrix A in A*X=B, of dimension (A->nrow, A->ncol). The number
        of linear equations is A->nrow. Currently, the type of A can be:
        Stype = SLU_NC or SLU_NR; Dtype = SLU_D; Mtype = SLU_GE.
        In the future, more general A may be handled.

perm_c  (input/output) int*
        If A->Stype = SLU_NC, column permutation vector of size A->ncol
        which defines the permutation matrix Pc; perm_c[i] = j means 
        column i of A is in position j in A*Pc.
        If A->Stype = SLU_NR, column permutation vector of size A->nrow
        which describes permutation of columns of transpose(A) 
        (rows of A) as described above.

        If options->ColPerm = MY_PERMC or options->Fact = SamePattern or
           options->Fact = SamePattern_SameRowPerm, it is an input argument.
           On exit, perm_c may be overwritten by the product of the input
           perm_c and a permutation that postorders the elimination tree
           of Pc'*A'*A*Pc; perm_c is not changed if the elimination tree
           is already in postorder.
        Otherwise, it is an output argument.

perm_r  (input/output) int*
        If A->Stype = SLU_NC, row permutation vector of size A->nrow, 
        which defines the permutation matrix Pr, and is determined 
        by partial pivoting.  perm_r[i] = j means row i of A is in 
        position j in Pr*A.
        If A->Stype = SLU_NR, permutation vector of size A->ncol, which
        determines permutation of rows of transpose(A)
        (columns of A) as described above.

        If options->RowPerm = MY_PERMR or
           options->Fact = SamePattern_SameRowPerm, perm_r is an
           input argument.
        otherwise it is an output argument.

L       (output) SuperMatrix*
        The factor L from the factorization 
            Pr*A*Pc=L*U              (if A->Stype = SLU_NC) or
            Pr*transpose(A)*Pc=L*U   (if A->Stype = SLU_NR).
        Uses compressed row subscripts storage for supernodes, i.e.,
        L has types: Stype = SLU_SC, Dtype = SLU_D, Mtype = SLU_TRLU.

U       (output) SuperMatrix*
        The factor U from the factorization 
            Pr*A*Pc=L*U              (if A->Stype = SLU_NC) or
            Pr*transpose(A)*Pc=L*U   (if A->Stype = SLU_NR).
        Uses column-wise storage scheme, i.e., U has types:
        Stype = SLU_NC, Dtype = SLU_D, Mtype = SLU_TRU.

B       (input/output) SuperMatrix*
        B has types: Stype = SLU_DN, Dtype = SLU_D, Mtype = SLU_GE.
        On entry, the right hand side matrix.
        On exit, the solution matrix if info = 0;

stat   (output) SuperLUStat_t*
       Record the statistics on runtime and floating-point operation count.
       See util.h for the definition of 'SuperLUStat_t'.

info    (output) int*
        = 0: successful exit
        > 0: if info = i, and i is
            <= A->ncol: U(i,i) is exactly zero. The factorization has
               been completed, but the factor U is exactly singular,
               so the solution could not be computed.
            > A->ncol: number of bytes allocated when memory allocation
               failure occurred, plus A->ncol.

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void dgssvx	(	superlu_options_t *	options,
		SuperMatrix *	A,
		int *	perm_c,
		int *	perm_r,
		int *	etree,
		char *	equed,
		double *	R,
		double *	C,
		SuperMatrix *	L,
		SuperMatrix *	U,
		void *	work,
		int	lwork,
		SuperMatrix *	B,
		SuperMatrix *	X,
		double *	recip_pivot_growth,
		double *	rcond,
		double *	ferr,
		double *	berr,
		GlobalLU_t *	Glu,
		mem_usage_t *	mem_usage,
		SuperLUStat_t *	stat,
		int *	info
	)

Purpose

DGSSVX solves the system of linear equations A*X=B or A'*X=B, using
the LU factorization from dgstrf(). Error bounds on the solution and
a condition estimate are also provided. It performs the following steps:

  1. If A is stored column-wise (A->Stype = SLU_NC):

     1.1. If options->Equil = YES, scaling factors are computed to
          equilibrate the system:
          options->Trans = NOTRANS:
              diag(R)*A*diag(C) *inv(diag(C))*X = diag(R)*B
          options->Trans = TRANS:
              (diag(R)*A*diag(C))**T *inv(diag(R))*X = diag(C)*B
          options->Trans = CONJ:
              (diag(R)*A*diag(C))**H *inv(diag(R))*X = diag(C)*B
          Whether or not the system will be equilibrated depends on the
          scaling of the matrix A, but if equilibration is used, A is
          overwritten by diag(R)*A*diag(C) and B by diag(R)*B
          (if options->Trans=NOTRANS) or diag(C)*B (if options->Trans
          = TRANS or CONJ).

     1.2. Permute columns of A, forming A*Pc, where Pc is a permutation
          matrix that usually preserves sparsity.
          For more details of this step, see sp_preorder.c.

     1.3. If options->Fact != FACTORED, the LU decomposition is used to
          factor the matrix A (after equilibration if options->Equil = YES)
          as Pr*A*Pc = L*U, with Pr determined by partial pivoting.

     1.4. Compute the reciprocal pivot growth factor.

     1.5. If some U(i,i) = 0, so that U is exactly singular, then the
          routine returns with info = i. Otherwise, the factored form of 
          A is used to estimate the condition number of the matrix A. If
          the reciprocal of the condition number is less than machine
          precision, info = A->ncol+1 is returned as a warning, but the
          routine still goes on to solve for X and computes error bounds
          as described below.

     1.6. The system of equations is solved for X using the factored form
          of A.

     1.7. If options->IterRefine != NOREFINE, iterative refinement is
          applied to improve the computed solution matrix and calculate
          error bounds and backward error estimates for it.

     1.8. If equilibration was used, the matrix X is premultiplied by
          diag(C) (if options->Trans = NOTRANS) or diag(R)
          (if options->Trans = TRANS or CONJ) so that it solves the
          original system before equilibration.

  2. If A is stored row-wise (A->Stype = SLU_NR), apply the above algorithm
     to the transpose of A:

     2.1. If options->Equil = YES, scaling factors are computed to
          equilibrate the system:
          options->Trans = NOTRANS:
              diag(R)*A*diag(C) *inv(diag(C))*X = diag(R)*B
          options->Trans = TRANS:
              (diag(R)*A*diag(C))**T *inv(diag(R))*X = diag(C)*B
          options->Trans = CONJ:
              (diag(R)*A*diag(C))**H *inv(diag(R))*X = diag(C)*B
          Whether or not the system will be equilibrated depends on the
          scaling of the matrix A, but if equilibration is used, A' is
          overwritten by diag(R)*A'*diag(C) and B by diag(R)*B 
          (if trans='N') or diag(C)*B (if trans = 'T' or 'C').

     2.2. Permute columns of transpose(A) (rows of A), 
          forming transpose(A)*Pc, where Pc is a permutation matrix that 
          usually preserves sparsity.
          For more details of this step, see sp_preorder.c.

     2.3. If options->Fact != FACTORED, the LU decomposition is used to
          factor the transpose(A) (after equilibration if 
          options->Fact = YES) as Pr*transpose(A)*Pc = L*U with the
          permutation Pr determined by partial pivoting.

     2.4. Compute the reciprocal pivot growth factor.

     2.5. If some U(i,i) = 0, so that U is exactly singular, then the
          routine returns with info = i. Otherwise, the factored form 
          of transpose(A) is used to estimate the condition number of the
          matrix A. If the reciprocal of the condition number
          is less than machine precision, info = A->nrow+1 is returned as
          a warning, but the routine still goes on to solve for X and
          computes error bounds as described below.

     2.6. The system of equations is solved for X using the factored form
          of transpose(A).

     2.7. If options->IterRefine != NOREFINE, iterative refinement is
          applied to improve the computed solution matrix and calculate
          error bounds and backward error estimates for it.

     2.8. If equilibration was used, the matrix X is premultiplied by
          diag(C) (if options->Trans = NOTRANS) or diag(R) 
          (if options->Trans = TRANS or CONJ) so that it solves the
          original system before equilibration.

  See supermatrix.h for the definition of 'SuperMatrix' structure.

Arguments

options (input) superlu_options_t*
        The structure defines the input parameters to control
        how the LU decomposition will be performed and how the
        system will be solved.

A       (input/output) SuperMatrix*
        Matrix A in A*X=B, of dimension (A->nrow, A->ncol). The number
        of the linear equations is A->nrow. Currently, the type of A can be:
        Stype = SLU_NC or SLU_NR, Dtype = SLU_D, Mtype = SLU_GE.
        In the future, more general A may be handled.

        On entry, If options->Fact = FACTORED and equed is not 'N', 
        then A must have been equilibrated by the scaling factors in
        R and/or C.  
        On exit, A is not modified if options->Equil = NO, or if 
        options->Equil = YES but equed = 'N' on exit.
        Otherwise, if options->Equil = YES and equed is not 'N',
        A is scaled as follows:
        If A->Stype = SLU_NC:
          equed = 'R':  A := diag(R) * A
          equed = 'C':  A := A * diag(C)
          equed = 'B':  A := diag(R) * A * diag(C).
        If A->Stype = SLU_NR:
          equed = 'R':  transpose(A) := diag(R) * transpose(A)
          equed = 'C':  transpose(A) := transpose(A) * diag(C)
          equed = 'B':  transpose(A) := diag(R) * transpose(A) * diag(C).

perm_c  (input/output) int*
        If A->Stype = SLU_NC, Column permutation vector of size A->ncol,
        which defines the permutation matrix Pc; perm_c[i] = j means
        column i of A is in position j in A*Pc.
        On exit, perm_c may be overwritten by the product of the input
        perm_c and a permutation that postorders the elimination tree
        of Pc'*A'*A*Pc; perm_c is not changed if the elimination tree
        is already in postorder.

        If A->Stype = SLU_NR, column permutation vector of size A->nrow,
        which describes permutation of columns of transpose(A) 
        (rows of A) as described above.

perm_r  (input/output) int*
        If A->Stype = SLU_NC, row permutation vector of size A->nrow, 
        which defines the permutation matrix Pr, and is determined
        by partial pivoting.  perm_r[i] = j means row i of A is in 
        position j in Pr*A.

        If A->Stype = SLU_NR, permutation vector of size A->ncol, which
        determines permutation of rows of transpose(A)
        (columns of A) as described above.

        If options->Fact = SamePattern_SameRowPerm, the pivoting routine
        will try to use the input perm_r, unless a certain threshold
        criterion is violated. In that case, perm_r is overwritten by a
        new permutation determined by partial pivoting or diagonal
        threshold pivoting.
        Otherwise, perm_r is output argument.

etree   (input/output) int*,  dimension (A->ncol)
        Elimination tree of Pc'*A'*A*Pc.
        If options->Fact != FACTORED and options->Fact != DOFACT,
        etree is an input argument, otherwise it is an output argument.
        Note: etree is a vector of parent pointers for a forest whose
        vertices are the integers 0 to A->ncol-1; etree[root]==A->ncol.

equed   (input/output) char*
        Specifies the form of equilibration that was done.
        = 'N': No equilibration.
        = 'R': Row equilibration, i.e., A was premultiplied by diag(R).
        = 'C': Column equilibration, i.e., A was postmultiplied by diag(C).
        = 'B': Both row and column equilibration, i.e., A was replaced 
               by diag(R)*A*diag(C).
        If options->Fact = FACTORED, equed is an input argument,
        otherwise it is an output argument.

R       (input/output) double*, dimension (A->nrow)
        The row scale factors for A or transpose(A).
        If equed = 'R' or 'B', A (if A->Stype = SLU_NC) or transpose(A)
            (if A->Stype = SLU_NR) is multiplied on the left by diag(R).
        If equed = 'N' or 'C', R is not accessed.
        If options->Fact = FACTORED, R is an input argument,
            otherwise, R is output.
        If options->zFact = FACTORED and equed = 'R' or 'B', each element
            of R must be positive.

C       (input/output) double*, dimension (A->ncol)
        The column scale factors for A or transpose(A).
        If equed = 'C' or 'B', A (if A->Stype = SLU_NC) or transpose(A)
            (if A->Stype = SLU_NR) is multiplied on the right by diag(C).
        If equed = 'N' or 'R', C is not accessed.
        If options->Fact = FACTORED, C is an input argument,
            otherwise, C is output.
        If options->Fact = FACTORED and equed = 'C' or 'B', each element
            of C must be positive.

L       (output) SuperMatrix*
        The factor L from the factorization
            Pr*A*Pc=L*U              (if A->Stype SLU_= NC) or
            Pr*transpose(A)*Pc=L*U   (if A->Stype = SLU_NR).
        Uses compressed row subscripts storage for supernodes, i.e.,
        L has types: Stype = SLU_SC, Dtype = SLU_D, Mtype = SLU_TRLU.

U       (output) SuperMatrix*
        The factor U from the factorization
            Pr*A*Pc=L*U              (if A->Stype = SLU_NC) or
            Pr*transpose(A)*Pc=L*U   (if A->Stype = SLU_NR).
        Uses column-wise storage scheme, i.e., U has types:
        Stype = SLU_NC, Dtype = SLU_D, Mtype = SLU_TRU.

work    (workspace/output) void*, size (lwork) (in bytes)
        User supplied workspace, should be large enough
        to hold data structures for factors L and U.
        On exit, if fact is not 'F', L and U point to this array.

lwork   (input) int
        Specifies the size of work array in bytes.
        = 0:  allocate space internally by system malloc;
        > 0:  use user-supplied work array of length lwork in bytes,
              returns error if space runs out.
        = -1: the routine guesses the amount of space needed without
              performing the factorization, and returns it in
              mem_usage->total_needed; no other side effects.

        See argument 'mem_usage' for memory usage statistics.

B       (input/output) SuperMatrix*
        B has types: Stype = SLU_DN, Dtype = SLU_D, Mtype = SLU_GE.
        On entry, the right hand side matrix.
        If B->ncol = 0, only LU decomposition is performed, the triangular
                        solve is skipped.
        On exit,
           if equed = 'N', B is not modified; otherwise
           if A->Stype = SLU_NC:
              if options->Trans = NOTRANS and equed = 'R' or 'B',
                 B is overwritten by diag(R)*B;
              if options->Trans = TRANS or CONJ and equed = 'C' of 'B',
                 B is overwritten by diag(C)*B;
           if A->Stype = SLU_NR:
              if options->Trans = NOTRANS and equed = 'C' or 'B',
                 B is overwritten by diag(C)*B;
              if options->Trans = TRANS or CONJ and equed = 'R' of 'B',
                 B is overwritten by diag(R)*B.

X       (output) SuperMatrix*
        X has types: Stype = SLU_DN, Dtype = SLU_D, Mtype = SLU_GE. 
        If info = 0 or info = A->ncol+1, X contains the solution matrix
        to the original system of equations. Note that A and B are modified
        on exit if equed is not 'N', and the solution to the equilibrated
        system is inv(diag(C))*X if options->Trans = NOTRANS and
        equed = 'C' or 'B', or inv(diag(R))*X if options->Trans = 'T' or 'C'
        and equed = 'R' or 'B'.

recip_pivot_growth (output) double*
        The reciprocal pivot growth factor max_j( norm(A_j)/norm(U_j) ).
        The infinity norm is used. If recip_pivot_growth is much less
        than 1, the stability of the LU factorization could be poor.

rcond   (output) double*
        The estimate of the reciprocal condition number of the matrix A
        after equilibration (if done). If rcond is less than the machine
        precision (in particular, if rcond = 0), the matrix is singular
        to working precision. This condition is indicated by a return
        code of info > 0.

FERR    (output) double*, dimension (B->ncol)   
        The estimated forward error bound for each solution vector   
        X(j) (the j-th column of the solution matrix X).   
        If XTRUE is the true solution corresponding to X(j), FERR(j) 
        is an estimated upper bound for the magnitude of the largest 
        element in (X(j) - XTRUE) divided by the magnitude of the   
        largest element in X(j).  The estimate is as reliable as   
        the estimate for RCOND, and is almost always a slight   
        overestimate of the true error.
        If options->IterRefine = NOREFINE, ferr = 1.0.

BERR    (output) double*, dimension (B->ncol)
        The componentwise relative backward error of each solution   
        vector X(j) (i.e., the smallest relative change in   
        any element of A or B that makes X(j) an exact solution).
        If options->IterRefine = NOREFINE, berr = 1.0.

Glu      (input/output) GlobalLU_t *
         If options->Fact == SamePattern_SameRowPerm, it is an input;
             The matrix A will be factorized assuming that a 
             factorization of a matrix with the same sparsity pattern
             and similar numerical values was performed prior to this one.
             Therefore, this factorization will reuse both row and column
        scaling factors R and C, both row and column permutation
        vectors perm_r and perm_c, and the L & U data structures
        set up from the previous factorization.
         Otherwise, it is an output.

mem_usage (output) mem_usage_t* Record the memory usage statistics, consisting of following fields:

for_lu (float) The amount of space used in bytes for L data structures.
total_needed (float) The amount of space needed in bytes to perform factorization.
expansions (int) The number of memory expansions during the LU factorization.

stat   (output) SuperLUStat_t*
       Record the statistics on runtime and floating-point operation count.
       See slu_util.h for the definition of 'SuperLUStat_t'.

info    (output) int*
        = 0: successful exit   
        < 0: if info = -i, the i-th argument had an illegal value   
        > 0: if info = i, and i is   
             <= A->ncol: U(i,i) is exactly zero. The factorization has   
                   been completed, but the factor U is exactly   
                   singular, so the solution and error bounds   
                   could not be computed.   
             = A->ncol+1: U is nonsingular, but RCOND is less than machine
                   precision, meaning that the matrix is singular to
                   working precision. Nevertheless, the solution and
                   error bounds are computed because there are a number
                   of situations where the computed solution can be more
                   accurate than the value of RCOND would suggest.   
             > A->ncol+1: number of bytes allocated when memory allocation
                   failure occurred, plus A->ncol.

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void dgstrf	(	superlu_options_t *	options,
		SuperMatrix *	A,
		int	relax,
		int	panel_size,
		int *	etree,
		void *	work,
		int	lwork,
		int *	perm_c,
		int *	perm_r,
		SuperMatrix *	L,
		SuperMatrix *	U,
		GlobalLU_t *	Glu,
		SuperLUStat_t *	stat,
		int *	info
	)

Purpose

DGSTRF computes an LU factorization of a general sparse m-by-n
matrix A using partial pivoting with row interchanges.
The factorization has the form
    Pr * A = L * U
where Pr is a row permutation matrix, L is lower triangular with unit
diagonal elements (lower trapezoidal if A->nrow > A->ncol), and U is upper 
triangular (upper trapezoidal if A->nrow < A->ncol).

See supermatrix.h for the definition of 'SuperMatrix' structure.

Arguments

options (input) superlu_options_t*
        The structure defines the input parameters to control
        how the LU decomposition will be performed.

A        (input) SuperMatrix*
         Original matrix A, permuted by columns, of dimension
         (A->nrow, A->ncol). The type of A can be:
         Stype = SLU_NCP; Dtype = SLU_D; Mtype = SLU_GE.

relax    (input) int
         To control degree of relaxing supernodes. If the number
         of nodes (columns) in a subtree of the elimination tree is less
         than relax, this subtree is considered as one supernode,
         regardless of the row structures of those columns.

panel_size (input) int
         A panel consists of at most panel_size consecutive columns.

etree    (input) int*, dimension (A->ncol)
         Elimination tree of A'*A.
         Note: etree is a vector of parent pointers for a forest whose
         vertices are the integers 0 to A->ncol-1; etree[root]==A->ncol.
         On input, the columns of A should be permuted so that the
         etree is in a certain postorder.

work     (input/output) void*, size (lwork) (in bytes)
         User-supplied work space and space for the output data structures.
         Not referenced if lwork = 0;

lwork   (input) int
        Specifies the size of work array in bytes.
        = 0:  allocate space internally by system malloc;
        > 0:  use user-supplied work array of length lwork in bytes,
              returns error if space runs out.
        = -1: the routine guesses the amount of space needed without
              performing the factorization, and returns it in
              *info; no other side effects.

perm_c   (input) int*, dimension (A->ncol)
         Column permutation vector, which defines the 
         permutation matrix Pc; perm_c[i] = j means column i of A is 
         in position j in A*Pc.
         When searching for diagonal, perm_c[*] is applied to the
         row subscripts of A, so that diagonal threshold pivoting
         can find the diagonal of A, rather than that of A*Pc.

perm_r   (input/output) int*, dimension (A->nrow)
         Row permutation vector which defines the permutation matrix Pr,
         perm_r[i] = j means row i of A is in position j in Pr*A.
         If options->Fact == SamePattern_SameRowPerm, the pivoting routine
            will try to use the input perm_r, unless a certain threshold
            criterion is violated. In that case, perm_r is overwritten by
            a new permutation determined by partial pivoting or diagonal
            threshold pivoting.
         Otherwise, perm_r is output argument;

L        (output) SuperMatrix*
         The factor L from the factorization Pr*A=L*U; use compressed row 
         subscripts storage for supernodes, i.e., L has type: 
         Stype = SLU_SC, Dtype = SLU_D, Mtype = SLU_TRLU.

U        (output) SuperMatrix*
         The factor U from the factorization Pr*A*Pc=L*U. Use column-wise
         storage scheme, i.e., U has types: Stype = SLU_NC, 
         Dtype = SLU_D, Mtype = SLU_TRU.

Glu      (input/output) GlobalLU_t *
         If options->Fact == SamePattern_SameRowPerm, it is an input;
             The matrix A will be factorized assuming that a 
             factorization of a matrix with the same sparsity pattern
             and similar numerical values was performed prior to this one.
             Therefore, this factorization will reuse both row and column
        scaling factors R and C, both row and column permutation
        vectors perm_r and perm_c, and the L & U data structures
        set up from the previous factorization.
         Otherwise, it is an output.

stat     (output) SuperLUStat_t*
         Record the statistics on runtime and floating-point operation count.
         See slu_util.h for the definition of 'SuperLUStat_t'.

info     (output) int*
         = 0: successful exit
         < 0: if info = -i, the i-th argument had an illegal value
         > 0: if info = i, and i is
            <= A->ncol: U(i,i) is exactly zero. The factorization has
               been completed, but the factor U is exactly singular,
               and division by zero will occur if it is used to solve a
               system of equations.
            > A->ncol: number of bytes allocated when memory allocation
               failure occurred, plus A->ncol. If lwork = -1, it is
               the estimated amount of space needed, plus A->ncol.

Local Working Arrays:

  m = number of rows in the matrix
  n = number of columns in the matrix

  xprune[0:n-1]: xprune[*] points to locations in subscript 
     vector lsub[*]. For column i, xprune[i] denotes the point where 
     structural pruning begins. I.e. only xlsub[i],..,xprune[i]-1 need 
     to be traversed for symbolic factorization.

  marker[0:3*m-1]: marker[i] = j means that node i has been 
     reached when working on column j.
     Storage: relative to original row subscripts
     NOTE: There are 3 of them: marker/marker1 are used for panel dfs, 
           see dpanel_dfs.c; marker2 is used for inner-factorization,
           see dcolumn_dfs.c.

  parent[0:m-1]: parent vector used during dfs
     Storage: relative to new row subscripts

  xplore[0:m-1]: xplore[i] gives the location of the next (dfs) 
     unexplored neighbor of i in lsub[*]

  segrep[0:nseg-1]: contains the list of supernodal representatives
     in topological order of the dfs. A supernode representative is the 
     last column of a supernode.
     The maximum size of segrep[] is n.

  repfnz[0:W*m-1]: for a nonzero segment U[*,j] that ends at a 
     supernodal representative r, repfnz[r] is the location of the first 
     nonzero in this segment.  It is also used during the dfs: repfnz[r]>0
     indicates the supernode r has been explored.
     NOTE: There are W of them, each used for one column of a panel.

  panel_lsub[0:W*m-1]: temporary for the nonzeros row indices below 
     the panel diagonal. These are filled in during dpanel_dfs(), and are
     used later in the inner LU factorization within the panel.
     panel_lsub[]/dense[] pair forms the SPA data structure.
     NOTE: There are W of them.

  dense[0:W*m-1]: sparse accumulating (SPA) vector for intermediate values;
                   NOTE: there are W of them.

  tempv[0:*]: real temporary used for dense numeric kernels;
     The size of this array is defined by NUM_TEMPV() in slu_ddefs.h.

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void dgstrs	(	trans_t	trans,
		SuperMatrix *	L,
		SuperMatrix *	U,
		int *	perm_c,
		int *	perm_r,
		SuperMatrix *	B,
		SuperLUStat_t *	stat,
		int *	info
	)

Purpose

DGSTRS solves a system of linear equations A*X=B or A'*X=B
with A sparse and B dense, using the LU factorization computed by
DGSTRF.

See supermatrix.h for the definition of 'SuperMatrix' structure.

Arguments

trans   (input) trans_t
         Specifies the form of the system of equations:
         = NOTRANS: A * X = B  (No transpose)
         = TRANS:   A'* X = B  (Transpose)
         = CONJ:    A**H * X = B  (Conjugate transpose)

L       (input) SuperMatrix*
        The factor L from the factorization Pr*A*Pc=L*U as computed by
        dgstrf(). Use compressed row subscripts storage for supernodes,
        i.e., L has types: Stype = SLU_SC, Dtype = SLU_D, Mtype = SLU_TRLU.

U       (input) SuperMatrix*
        The factor U from the factorization Pr*A*Pc=L*U as computed by
        dgstrf(). Use column-wise storage scheme, i.e., U has types:
        Stype = SLU_NC, Dtype = SLU_D, Mtype = SLU_TRU.

perm_c  (input) int*, dimension (L->ncol)
        Column permutation vector, which defines the 
        permutation matrix Pc; perm_c[i] = j means column i of A is 
        in position j in A*Pc.

perm_r  (input) int*, dimension (L->nrow)
        Row permutation vector, which defines the permutation matrix Pr; 
        perm_r[i] = j means row i of A is in position j in Pr*A.

B       (input/output) SuperMatrix*
        B has types: Stype = SLU_DN, Dtype = SLU_D, Mtype = SLU_GE.
        On entry, the right hand side matrix.
        On exit, the solution matrix if info = 0;

stat     (output) SuperLUStat_t*
         Record the statistics on runtime and floating-point operation count.
         See util.h for the definition of 'SuperLUStat_t'.

info    (output) int*
           = 0: successful exit
        < 0: if info = -i, the i-th argument had an illegal value

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void dinf_norm_error	(	int	,
		SuperMatrix *	,
		double *
	)

void dlaqgs	(	SuperMatrix *	A,
		double *	r,
		double *	c,
		double	rowcnd,
		double	colcnd,
		double	amax,
		char *	equed
	)

Purpose

  DLAQGS equilibrates a general sparse M by N matrix A using the row and   
  scaling factors in the vectors R and C.

  See supermatrix.h for the definition of 'SuperMatrix' structure.

Arguments

  A       (input/output) SuperMatrix*
          On exit, the equilibrated matrix.  See EQUED for the form of 
          the equilibrated matrix. The type of A can be:
         Stype = NC; Dtype = SLU_D; Mtype = GE.

  R       (input) double*, dimension (A->nrow)
          The row scale factors for A.

  C       (input) double*, dimension (A->ncol)
          The column scale factors for A.

  ROWCND  (input) double
          Ratio of the smallest R(i) to the largest R(i).

  COLCND  (input) double
          Ratio of the smallest C(i) to the largest C(i).

  AMAX    (input) double
          Absolute value of largest matrix entry.

  EQUED   (output) char*
          Specifies the form of equilibration that was done.   
          = 'N':  No equilibration   
          = 'R':  Row equilibration, i.e., A has been premultiplied by  
                  diag(R).   
          = 'C':  Column equilibration, i.e., A has been postmultiplied  
                  by diag(C).   
          = 'B':  Both row and column equilibration, i.e., A has been
                  replaced by diag(R) * A * diag(C).

Internal Parameters

  THRESH is a threshold value used to decide if row or column scaling   
  should be done based on the ratio of the row or column scaling   
  factors.  If ROWCND < THRESH, row scaling is done, and if   
  COLCND < THRESH, column scaling is done.

LARGE and SMALL are threshold values used to decide if row scaling should be done based on the absolute size of the largest matrix element. If AMAX > LARGE or AMAX < SMALL, row scaling is done.

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int dldperm	(	int	,
		int	,
		int	,
		int	[],
		int	[],
		double	[],
		int	[],
		double	[],
		double	[]
	)

int dLUMemInit	(	fact_t	fact,
		void *	work,
		int	lwork,
		int	m,
		int	n,
		int	annz,
		int	panel_size,
		double	fill_ratio,
		SuperMatrix *	L,
		SuperMatrix *	U,
		GlobalLU_t *	Glu,
		int **	iwork,
		double **	dwork
	)

Memory-related.

For those unpredictable size, estimate as fill_ratio * nnz(A).
Return value:
    If lwork = -1, return the estimated amount of space required, plus n;
    otherwise, return the amount of space actually allocated when
    memory allocation failure occurred.

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int dLUMemXpand	(	int	jcol,
		int	next,
		MemType	mem_type,
		int *	maxlen,
		GlobalLU_t *	Glu
	)

Return value:   0 - successful return
              > 0 - number of bytes allocated when run out of space

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void dLUWorkFree	(	int *	,
		double *	,
		GlobalLU_t *
	)

double dmach ( char * )

int dmemory_usage	(	const int	,
		const int	,
		const int	,
		const int
	)

double* doubleCalloc ( int )

double* doubleMalloc ( int )

void dpanel_bmod	(	const int	m,
		const int	w,
		const int	jcol,
		const int	nseg,
		double *	dense,
		double *	tempv,
		int *	segrep,
		int *	repfnz,
		GlobalLU_t *	Glu,
		SuperLUStat_t *	stat
	)

Purpose

   Performs numeric block updates (sup-panel) in topological order.
   It features: col-col, 2cols-col, 3cols-col, and sup-col updates.
   Special processing on the supernodal portion of L[*,j]

   Before entering this routine, the original nonzeros in the panel 
   were already copied into the spa[m,w].

   Updated/Output parameters-
   dense[0:m-1,w]: L[*,j:j+w-1] and U[*,j:j+w-1] are returned 
   collectively in the m-by-w vector dense[*].

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void dpanel_dfs	(	const int	m,
		const int	w,
		const int	jcol,
		SuperMatrix *	A,
		int *	perm_r,
		int *	nseg,
		double *	dense,
		int *	panel_lsub,
		int *	segrep,
		int *	repfnz,
		int *	xprune,
		int *	marker,
		int *	parent,
		int *	xplore,
		GlobalLU_t *	Glu
	)

Purpose

  Performs a symbolic factorization on a panel of columns [jcol, jcol+w).

  A supernode representative is the last column of a supernode.
  The nonzeros in U[*,j] are segments that end at supernodal
  representatives.

  The routine returns one list of the supernodal representatives
  in topological order of the dfs that generates them. This list is
  a superset of the topological order of each individual column within
  the panel. 
  The location of the first nonzero in each supernodal segment
  (supernodal entry location) is also returned. Each column has a 
  separate list for this purpose.

  Two marker arrays are used for dfs:
    marker[i] == jj, if i was visited during dfs of current column jj;
    marker1[i] >= jcol, if i was visited by earlier columns in this panel;

  marker: A-row –> A-row/col (0/1)
  repfnz: SuperA-col –> PA-row
  parent: SuperA-col –> SuperA-col
  xplore: SuperA-col –> index to L-structure

double dPivotGrowth	(	int	ncols,
		SuperMatrix *	A,
		int *	perm_c,
		SuperMatrix *	L,
		SuperMatrix *	U
	)

Purpose

Compute the reciprocal pivot growth factor of the leading ncols columns
of the matrix, using the formula:
    min_j ( max_i(abs(A_ij)) / max_i(abs(U_ij)) )

Arguments

ncols    (input) int
         The number of columns of matrices A, L and U.

A        (input) SuperMatrix*
         Original matrix A, permuted by columns, of dimension
         (A->nrow, A->ncol). The type of A can be:
         Stype = NC; Dtype = SLU_D; Mtype = GE.

L        (output) SuperMatrix*
         The factor L from the factorization Pr*A=L*U; use compressed row 
         subscripts storage for supernodes, i.e., L has type: 
         Stype = SC; Dtype = SLU_D; Mtype = TRLU.

U        (output) SuperMatrix*
         The factor U from the factorization Pr*A*Pc=L*U. Use column-wise
         storage scheme, i.e., U has types: Stype = NC;
         Dtype = SLU_D; Mtype = TRU.

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int dpivotL	(	const int	jcol,
		const double	u,
		int *	usepr,
		int *	perm_r,
		int *	iperm_r,
		int *	iperm_c,
		int *	pivrow,
		GlobalLU_t *	Glu,
		SuperLUStat_t *	stat
	)

Purpose

  Performs the numerical pivoting on the current column of L,
  and the CDIV operation.

  Pivot policy:
  (1) Compute thresh = u * max_(i>=j) abs(A_ij);
  (2) IF user specifies pivot row k and abs(A_kj) >= thresh THEN
          pivot row = k;
      ELSE IF abs(A_jj) >= thresh THEN
          pivot row = j;
      ELSE
          pivot row = m;

  Note: If you absolutely want to use a given pivot order, then set u=0.0.

  Return value: 0      success;
                i > 0  U(i,i) is exactly zero.

void dPrint_CompCol_Matrix	(	char *	,
		SuperMatrix *
	)

void dPrint_Dense_Matrix	(	char *	,
		SuperMatrix *
	)

void dprint_lu_col	(	char *	,
		int	,
		int	,
		int *	,
		GlobalLU_t *
	)

void dPrint_SuperNode_Matrix	(	char *	,
		SuperMatrix *
	)

void dpruneL	(	const int	jcol,
		const int *	perm_r,
		const int	pivrow,
		const int	nseg,
		const int *	segrep,
		const int *	repfnz,
		int *	xprune,
		GlobalLU_t *	Glu
	)

Purpose

  Prunes the L-structure of supernodes whose L-structure
  contains the current pivot row "pivrow"

double dqselect	(	int	,
		double *	,
		int
	)

int dQuerySpace	(	SuperMatrix *	L,
		SuperMatrix *	U,
		mem_usage_t *	mem_usage
	)

mem_usage consists of the following fields:

for_lu (float) The amount of space used in bytes for the L data structures.
total_needed (float) The amount of space needed in bytes to perform factorization.

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void dreadhb	(	FILE *	,
		int *	,
		int *	,
		int *	,
		double **	,
		int **	,
		int **
	)

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void dreadmt	(	int *	,
		int *	,
		int *	,
		double **	,
		int **	,
		int **
	)

void dreadrb	(	int *	,
		int *	,
		int *	,
		double **	,
		int **	,
		int **
	)

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void dreadtriple	(	int *	,
		int *	,
		int *	,
		double **	,
		int **	,
		int **
	)

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void dSetRWork	(	int	,
		int	,
		double *	,
		double **	,
		double **
	)

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int dsnode_bmod	(	const int	,
		const int	,
		const int	,
		double *	,
		double *	,
		GlobalLU_t *	,
		SuperLUStat_t *
	)

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int dsnode_dfs	(	const int	jcol,
		const int	kcol,
		const int *	asub,
		const int *	xa_begin,
		const int *	xa_end,
		int *	xprune,
		int *	marker,
		GlobalLU_t *	Glu
	)

Purpose

   dsnode_dfs() - Determine the union of the row structures of those 
   columns within the relaxed snode.
   Note: The relaxed snodes are leaves of the supernodal etree, therefore, 
   the portion outside the rectangular supernode must be zero.

Return value

    0   success;
   >0   number of bytes allocated when run out of memory.

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int dtrsm_	(	char *	,
		char *	,
		char *	,
		char *	,
		int *	,
		int *	,
		double *	,
		double *	,
		int *	,
		double *	,
		int *
	)

int dtrsv_	(	char *	,
		char *	,
		char *	,
		int *	,
		double *	,
		int *	,
		double *	,
		int *
	)

void fixupL	(	const int	,
		const int *	,
		GlobalLU_t *
	)

void ilu_countnz	(	const int	,
		int *	,
		int *	,
		GlobalLU_t *
	)

int ilu_dcolumn_dfs	(	const int	m,
		const int	jcol,
		int *	perm_r,
		int *	nseg,
		int *	lsub_col,
		int *	segrep,
		int *	repfnz,
		int *	marker,
		int *	parent,
		int *	xplore,
		GlobalLU_t *	Glu
	)

Purpose

  ILU_DCOLUMN_DFS performs a symbolic factorization on column jcol, and
  decide the supernode boundary.

  This routine does not use numeric values, but only use the RHS
  row indices to start the dfs.

  A supernode representative is the last column of a supernode.
  The nonzeros in U[*,j] are segments that end at supernodal
  representatives. The routine returns a list of such supernodal
  representatives in topological order of the dfs that generates them.
  The location of the first nonzero in each such supernodal segment
  (supernodal entry location) is also returned.

Local parameters

  nseg: no of segments in current U[*,j]
  jsuper: jsuper=EMPTY if column j does not belong to the same
     supernode as j-1. Otherwise, jsuper=nsuper.

  marker2: A-row –> A-row/col (0/1)
  repfnz: SuperA-col –> PA-row
  parent: SuperA-col –> SuperA-col
  xplore: SuperA-col –> index to L-structure

Return value

0 success;

0 number of bytes allocated when run out of space.

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int ilu_dcopy_to_ucol	(	int	,
		int	,
		int *	,
		int *	,
		int *	,
		double *	,
		int	,
		milu_t	,
		double	,
		int	,
		double *	,
		int *	,
		GlobalLU_t *	,
		double *
	)

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int ilu_ddrop_row	(	superlu_options_t *	,
		int	,
		int	,
		double	,
		int	,
		int *	,
		double *	,
		GlobalLU_t *	,
		double *	,
		double *	,
		int
	)

void ilu_dpanel_dfs	(	const int	m,
		const int	w,
		const int	jcol,
		SuperMatrix *	A,
		int *	perm_r,
		int *	nseg,
		double *	dense,
		double *	amax,
		int *	panel_lsub,
		int *	segrep,
		int *	repfnz,
		int *	marker,
		int *	parent,
		int *	xplore,
		GlobalLU_t *	Glu
	)

Purpose

  Performs a symbolic factorization on a panel of columns [jcol, jcol+w).

  A supernode representative is the last column of a supernode.
  The nonzeros in U[*,j] are segments that end at supernodal
  representatives.

  The routine returns one list of the supernodal representatives
  in topological order of the dfs that generates them. This list is
  a superset of the topological order of each individual column within
  the panel.
  The location of the first nonzero in each supernodal segment
  (supernodal entry location) is also returned. Each column has a
  separate list for this purpose.

  Two marker arrays are used for dfs:
    marker[i] == jj, if i was visited during dfs of current column jj;
    marker1[i] >= jcol, if i was visited by earlier columns in this panel;

  marker: A-row –> A-row/col (0/1)
  repfnz: SuperA-col –> PA-row
  parent: SuperA-col –> SuperA-col
  xplore: SuperA-col –> index to L-structure

int ilu_dpivotL	(	const int	jcol,
		const double	u,
		int *	usepr,
		int *	perm_r,
		int	diagind,
		int *	swap,
		int *	iswap,
		int *	marker,
		int *	pivrow,
		double	fill_tol,
		milu_t	milu,
		double	drop_sum,
		GlobalLU_t *	Glu,
		SuperLUStat_t *	stat
	)

Purpose

  Performs the numerical pivoting on the current column of L,
  and the CDIV operation.

  Pivot policy:
  (1) Compute thresh = u * max_(i>=j) abs(A_ij);
  (2) IF user specifies pivot row k and abs(A_kj) >= thresh THEN
          pivot row = k;
      ELSE IF abs(A_jj) >= thresh THEN
          pivot row = j;
      ELSE
          pivot row = m;

  Note: If you absolutely want to use a given pivot order, then set u=0.0.

  Return value: 0         success;
           i > 0  U(i,i) is exactly zero.

int ilu_dQuerySpace	(	SuperMatrix *	L,
		SuperMatrix *	U,
		mem_usage_t *	mem_usage
	)

mem_usage consists of the following fields:

for_lu (float) The amount of space used in bytes for the L data structures.
total_needed (float) The amount of space needed in bytes to perform factorization.

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int ilu_dsnode_dfs	(	const int	jcol,
		const int	kcol,
		const int *	asub,
		const int *	xa_begin,
		const int *	xa_end,
		int *	marker,
		GlobalLU_t *	Glu
	)

Purpose

   ilu_dsnode_dfs() - Determine the union of the row structures of those
   columns within the relaxed snode.
   Note: The relaxed snodes are leaves of the supernodal etree, therefore,
   the portion outside the rectangular supernode must be zero.

Return value

    0   success;
   >0   number of bytes allocated when run out of memory.

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int print_double_vec	(	char *	,
		int	,
		double *
	)

int sp_dgemm	(	char *	transa,
		char *	transb,
		int	m,
		int	n,
		int	k,
		double	alpha,
		SuperMatrix *	A,
		double *	b,
		int	ldb,
		double	beta,
		double *	c,
		int	ldc
	)

Purpose

  sp_d performs one of the matrix-matrix operations

     C := alpha*op( A )*op( B ) + beta*C,

  where  op( X ) is one of

     op( X ) = X   or   op( X ) = X'   or   op( X ) = conjg( X' ),

  alpha and beta are scalars, and A, B and C are matrices, with op( A ) 
  an m by k matrix,  op( B )  a  k by n matrix and  C an m by n matrix.

Parameters

  TRANSA - (input) char*
           On entry, TRANSA specifies the form of op( A ) to be used in 
           the matrix multiplication as follows:   
              TRANSA = 'N' or 'n',  op( A ) = A.   
              TRANSA = 'T' or 't',  op( A ) = A'.   
              TRANSA = 'C' or 'c',  op( A ) = conjg( A' ).   
           Unchanged on exit.

  TRANSB - (input) char*
           On entry, TRANSB specifies the form of op( B ) to be used in 
           the matrix multiplication as follows:   
              TRANSB = 'N' or 'n',  op( B ) = B.   
              TRANSB = 'T' or 't',  op( B ) = B'.   
              TRANSB = 'C' or 'c',  op( B ) = conjg( B' ).   
           Unchanged on exit.

  M      - (input) int   
           On entry,  M  specifies  the number of rows of the matrix 
          op( A ) and of the matrix C.  M must be at least zero. 
          Unchanged on exit.

  N      - (input) int
           On entry,  N specifies the number of columns of the matrix 
          op( B ) and the number of columns of the matrix C. N must be 
          at least zero.
          Unchanged on exit.

  K      - (input) int
           On entry, K specifies the number of columns of the matrix 
          op( A ) and the number of rows of the matrix op( B ). K must 
          be at least  zero.   
          Unchanged on exit.

  ALPHA  - (input) double
           On entry, ALPHA specifies the scalar alpha.

  A      - (input) SuperMatrix*
           Matrix A with a sparse format, of dimension (A->nrow, A->ncol).
           Currently, the type of A can be:
               Stype = NC or NCP; Dtype = SLU_D; Mtype = GE. 
           In the future, more general A can be handled.

  B      - DOUBLE PRECISION array of DIMENSION ( LDB, kb ), where kb is 
           n when TRANSB = 'N' or 'n',  and is  k otherwise.   
           Before entry with  TRANSB = 'N' or 'n',  the leading k by n 
           part of the array B must contain the matrix B, otherwise 
           the leading n by k part of the array B must contain the 
           matrix B.   
           Unchanged on exit.

  LDB    - (input) int
           On entry, LDB specifies the first dimension of B as declared 
           in the calling (sub) program. LDB must be at least max( 1, n ).  
           Unchanged on exit.

  BETA   - (input) double
           On entry, BETA specifies the scalar beta. When BETA is   
           supplied as zero then C need not be set on input.

  C      - DOUBLE PRECISION array of DIMENSION ( LDC, n ).   
           Before entry, the leading m by n part of the array C must 
           contain the matrix C,  except when beta is zero, in which 
           case C need not be set on entry.   
           On exit, the array C is overwritten by the m by n matrix 
          ( alpha*op( A )*B + beta*C ).

  LDC    - (input) int
           On entry, LDC specifies the first dimension of C as declared 
           in the calling (sub)program. LDC must be at least max(1,m).   
           Unchanged on exit.

  ==== Sparse Level 3 Blas routine.

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int sp_dgemv	(	char *	trans,
		double	alpha,
		SuperMatrix *	A,
		double *	x,
		int	incx,
		double	beta,
		double *	y,
		int	incy
	)

Purpose

  sp_dgemv()  performs one of the matrix-vector operations   
     y := alpha*A*x + beta*y,   or   y := alpha*A'*x + beta*y,   
  where alpha and beta are scalars, x and y are vectors and A is a
  sparse A->nrow by A->ncol matrix.

Parameters

  TRANS  - (input) char*
           On entry, TRANS specifies the operation to be performed as   
           follows:   
              TRANS = 'N' or 'n'   y := alpha*A*x + beta*y.   
              TRANS = 'T' or 't'   y := alpha*A'*x + beta*y.   
              TRANS = 'C' or 'c'   y := alpha*A'*x + beta*y.

  ALPHA  - (input) double
           On entry, ALPHA specifies the scalar alpha.

  A      - (input) SuperMatrix*
           Matrix A with a sparse format, of dimension (A->nrow, A->ncol).
           Currently, the type of A can be:
               Stype = NC or NCP; Dtype = SLU_D; Mtype = GE. 
           In the future, more general A can be handled.

  X      - (input) double*, array of DIMENSION at least   
           ( 1 + ( n - 1 )*abs( INCX ) ) when TRANS = 'N' or 'n'   
           and at least   
           ( 1 + ( m - 1 )*abs( INCX ) ) otherwise.   
           Before entry, the incremented array X must contain the   
           vector x.

  INCX   - (input) int
           On entry, INCX specifies the increment for the elements of   
           X. INCX must not be zero.

  BETA   - (input) double
           On entry, BETA specifies the scalar beta. When BETA is   
           supplied as zero then Y need not be set on input.

  Y      - (output) double*,  array of DIMENSION at least   
           ( 1 + ( m - 1 )*abs( INCY ) ) when TRANS = 'N' or 'n'   
           and at least   
           ( 1 + ( n - 1 )*abs( INCY ) ) otherwise.   
           Before entry with BETA non-zero, the incremented array Y   
           must contain the vector y. On exit, Y is overwritten by the 
           updated vector y.

  INCY   - (input) int
           On entry, INCY specifies the increment for the elements of   
           Y. INCY must not be zero.

  ==== Sparse Level 2 Blas routine.

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int sp_dtrsv	(	char *	uplo,
		char *	trans,
		char *	diag,
		SuperMatrix *	L,
		SuperMatrix *	U,
		double *	x,
		SuperLUStat_t *	stat,
		int *	info
	)

Purpose

  sp_dtrsv() solves one of the systems of equations   
      A*x = b,   or   A'*x = b,
  where b and x are n element vectors and A is a sparse unit , or   
  non-unit, upper or lower triangular matrix.   
  No test for singularity or near-singularity is included in this   
  routine. Such tests must be performed before calling this routine.

Parameters

  uplo   - (input) char*
           On entry, uplo specifies whether the matrix is an upper or   
            lower triangular matrix as follows:   
               uplo = 'U' or 'u'   A is an upper triangular matrix.   
               uplo = 'L' or 'l'   A is a lower triangular matrix.

  trans  - (input) char*
            On entry, trans specifies the equations to be solved as   
            follows:   
               trans = 'N' or 'n'   A*x = b.   
               trans = 'T' or 't'   A'*x = b.
               trans = 'C' or 'c'   A'*x = b.

  diag   - (input) char*
            On entry, diag specifies whether or not A is unit   
            triangular as follows:   
               diag = 'U' or 'u'   A is assumed to be unit triangular.   
               diag = 'N' or 'n'   A is not assumed to be unit   
                                   triangular.

  L       - (input) SuperMatrix*
            The factor L from the factorization Pr*A*Pc=L*U. Use
            compressed row subscripts storage for supernodes,
            i.e., L has types: Stype = SC, Dtype = SLU_D, Mtype = TRLU.

  U       - (input) SuperMatrix*
             The factor U from the factorization Pr*A*Pc=L*U.
             U has types: Stype = NC, Dtype = SLU_D, Mtype = TRU.

  x       - (input/output) double*
            Before entry, the incremented array X must contain the n   
            element right-hand side vector b. On exit, X is overwritten 
            with the solution vector x.

  info    - (output) int*
            If *info = -i, the i-th argument had an illegal value.

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