/*! \file
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.
*/

/*! @file smyblas2.c
 * \brief Level 2 Blas operations
 * 
 * <pre>
 * -- SuperLU routine (version 2.0) --
 * Univ. of California Berkeley, Xerox Palo Alto Research Center,
 * and Lawrence Berkeley National Lab.
 * November 15, 1997
 * </pre>
 * Purpose:
 *     Level 2 BLAS operations: solves and matvec, written in C.
 * Note:
 *     This is only used when the system lacks an efficient BLAS library.
 * </pre>
 */
/*
 * File name:		smyblas2.c
 */

/*! \brief Solves a dense UNIT lower triangular system
 *
 *  The unit lower 
 * triangular matrix is stored in a 2D array M(1:nrow,1:ncol). 
 * The solution will be returned in the rhs vector.
 */
void slsolve ( int ldm, int ncol, float *M, float *rhs )
{
    int k;
    float x0, x1, x2, x3, x4, x5, x6, x7;
    float *M0;
    register float *Mki0, *Mki1, *Mki2, *Mki3, *Mki4, *Mki5, *Mki6, *Mki7;
    register int firstcol = 0;

    M0 = &M[0];

    while ( firstcol < ncol - 7 ) { /* Do 8 columns */
      Mki0 = M0 + 1;
      Mki1 = Mki0 + ldm + 1;
      Mki2 = Mki1 + ldm + 1;
      Mki3 = Mki2 + ldm + 1;
      Mki4 = Mki3 + ldm + 1;
      Mki5 = Mki4 + ldm + 1;
      Mki6 = Mki5 + ldm + 1;
      Mki7 = Mki6 + ldm + 1;

      x0 = rhs[firstcol];
      x1 = rhs[firstcol+1] - x0 * *Mki0++;
      x2 = rhs[firstcol+2] - x0 * *Mki0++ - x1 * *Mki1++;
      x3 = rhs[firstcol+3] - x0 * *Mki0++ - x1 * *Mki1++ - x2 * *Mki2++;
      x4 = rhs[firstcol+4] - x0 * *Mki0++ - x1 * *Mki1++ - x2 * *Mki2++
	                   - x3 * *Mki3++;
      x5 = rhs[firstcol+5] - x0 * *Mki0++ - x1 * *Mki1++ - x2 * *Mki2++
	                   - x3 * *Mki3++ - x4 * *Mki4++;
      x6 = rhs[firstcol+6] - x0 * *Mki0++ - x1 * *Mki1++ - x2 * *Mki2++
	                   - x3 * *Mki3++ - x4 * *Mki4++ - x5 * *Mki5++;
      x7 = rhs[firstcol+7] - x0 * *Mki0++ - x1 * *Mki1++ - x2 * *Mki2++
	                   - x3 * *Mki3++ - x4 * *Mki4++ - x5 * *Mki5++
			   - x6 * *Mki6++;

      rhs[++firstcol] = x1;
      rhs[++firstcol] = x2;
      rhs[++firstcol] = x3;
      rhs[++firstcol] = x4;
      rhs[++firstcol] = x5;
      rhs[++firstcol] = x6;
      rhs[++firstcol] = x7;
      ++firstcol;
    
      for (k = firstcol; k < ncol; k++)
	rhs[k] = rhs[k] - x0 * *Mki0++ - x1 * *Mki1++
	                - x2 * *Mki2++ - x3 * *Mki3++
                        - x4 * *Mki4++ - x5 * *Mki5++
			- x6 * *Mki6++ - x7 * *Mki7++;
 
      M0 += 8 * ldm + 8;
    }

    while ( firstcol < ncol - 3 ) { /* Do 4 columns */
      Mki0 = M0 + 1;
      Mki1 = Mki0 + ldm + 1;
      Mki2 = Mki1 + ldm + 1;
      Mki3 = Mki2 + ldm + 1;

      x0 = rhs[firstcol];
      x1 = rhs[firstcol+1] - x0 * *Mki0++;
      x2 = rhs[firstcol+2] - x0 * *Mki0++ - x1 * *Mki1++;
      x3 = rhs[firstcol+3] - x0 * *Mki0++ - x1 * *Mki1++ - x2 * *Mki2++;

      rhs[++firstcol] = x1;
      rhs[++firstcol] = x2;
      rhs[++firstcol] = x3;
      ++firstcol;
    
      for (k = firstcol; k < ncol; k++)
	rhs[k] = rhs[k] - x0 * *Mki0++ - x1 * *Mki1++
	                - x2 * *Mki2++ - x3 * *Mki3++;
 
      M0 += 4 * ldm + 4;
    }

    if ( firstcol < ncol - 1 ) { /* Do 2 columns */
      Mki0 = M0 + 1;
      Mki1 = Mki0 + ldm + 1;

      x0 = rhs[firstcol];
      x1 = rhs[firstcol+1] - x0 * *Mki0++;

      rhs[++firstcol] = x1;
      ++firstcol;
    
      for (k = firstcol; k < ncol; k++)
	rhs[k] = rhs[k] - x0 * *Mki0++ - x1 * *Mki1++;
 
    }
    
}

/*! \brief Solves a dense upper triangular system
 * 
 * The upper triangular matrix is
 * stored in a 2-dim array M(1:ldm,1:ncol). The solution will be returned
 * in the rhs vector.
 */
void
susolve ( ldm, ncol, M, rhs )
int ldm;	/* in */
int ncol;	/* in */
float *M;	/* in */
float *rhs;	/* modified */
{
    float xj;
    int jcol, j, irow;

    jcol = ncol - 1;

    for (j = 0; j < ncol; j++) {

	xj = rhs[jcol] / M[jcol + jcol*ldm]; 		/* M(jcol, jcol) */
	rhs[jcol] = xj;
	
	for (irow = 0; irow < jcol; irow++)
	    rhs[irow] -= xj * M[irow + jcol*ldm];	/* M(irow, jcol) */

	jcol--;

    }
}


/*! \brief Performs a dense matrix-vector multiply: Mxvec = Mxvec + M * vec.
 * 
 * The input matrix is M(1:nrow,1:ncol); The product is returned in Mxvec[].
 */
void smatvec ( ldm, nrow, ncol, M, vec, Mxvec )

int ldm;	/* in -- leading dimension of M */
int nrow;	/* in */ 
int ncol;	/* in */
float *M;	/* in */
float *vec;	/* in */
float *Mxvec;	/* in/out */

{
    float vi0, vi1, vi2, vi3, vi4, vi5, vi6, vi7;
    float *M0;
    register float *Mki0, *Mki1, *Mki2, *Mki3, *Mki4, *Mki5, *Mki6, *Mki7;
    register int firstcol = 0;
    int k;

    M0 = &M[0];
    while ( firstcol < ncol - 7 ) {	/* Do 8 columns */

	Mki0 = M0;
	Mki1 = Mki0 + ldm;
        Mki2 = Mki1 + ldm;
        Mki3 = Mki2 + ldm;
	Mki4 = Mki3 + ldm;
	Mki5 = Mki4 + ldm;
	Mki6 = Mki5 + ldm;
	Mki7 = Mki6 + ldm;

	vi0 = vec[firstcol++];
	vi1 = vec[firstcol++];
	vi2 = vec[firstcol++];
	vi3 = vec[firstcol++];	
	vi4 = vec[firstcol++];
	vi5 = vec[firstcol++];
	vi6 = vec[firstcol++];
	vi7 = vec[firstcol++];	

	for (k = 0; k < nrow; k++) 
	    Mxvec[k] += vi0 * *Mki0++ + vi1 * *Mki1++
		      + vi2 * *Mki2++ + vi3 * *Mki3++ 
		      + vi4 * *Mki4++ + vi5 * *Mki5++
		      + vi6 * *Mki6++ + vi7 * *Mki7++;

	M0 += 8 * ldm;
    }

    while ( firstcol < ncol - 3 ) {	/* Do 4 columns */

	Mki0 = M0;
	Mki1 = Mki0 + ldm;
	Mki2 = Mki1 + ldm;
	Mki3 = Mki2 + ldm;

	vi0 = vec[firstcol++];
	vi1 = vec[firstcol++];
	vi2 = vec[firstcol++];
	vi3 = vec[firstcol++];	
	for (k = 0; k < nrow; k++) 
	    Mxvec[k] += vi0 * *Mki0++ + vi1 * *Mki1++
		      + vi2 * *Mki2++ + vi3 * *Mki3++ ;

	M0 += 4 * ldm;
    }

    while ( firstcol < ncol ) {		/* Do 1 column */

 	Mki0 = M0;
	vi0 = vec[firstcol++];
	for (k = 0; k < nrow; k++)
	    Mxvec[k] += vi0 * *Mki0++;

	M0 += ldm;
    }
	
}