dgscon.c File Reference

Estimates reciprocal of the condition number of a general matrix. More...

#include <math.h>
#include "slu_ddefs.h"

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

Detailed Description

Copyright (c) 2003, The Regents of the University of California, through Lawrence Berkeley National Laboratory (subject to receipt of any required approvals from U.S. Dept. of Energy)

All rights reserved.

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

-- SuperLU routine (version 5.0) --
Univ. of California Berkeley, Xerox Palo Alto Research Center,
and Lawrence Berkeley National Lab.
July 25, 2015

Modified from lapack routines DGECON.

Function Documentation

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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