
/*
 * -- SuperLU routine (version 2.0) --
 * Univ. of California Berkeley, Xerox Palo Alto Research Center,
 * and Lawrence Berkeley National Lab.
 * November 15, 1997
 *
 */
/*
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
*/
/*
  Copyright (c) 1997 by Xerox Corporation.  All rights reserved.
 
  THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY
  EXPRESSED OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
 
  Permission is hereby granted to use or copy this program for any
  purpose, provided the above notices are retained on all copies.
  Permission to modify the code and to distribute modified code is
  granted, provided the above notices are retained, and a notice that
  the code was modified is included with the above copyright notice.
*/
/*
 * File name:		zmyblas2.c
 * Purpose:
 *     Level 2 BLAS operations: solves and matvec, written in C.
 * Note:
 *     This is only used when the system lacks an efficient BLAS library.
 */
#include "slu_dcomplex.h"

/*
 * 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 zlsolve ( int ldm, int ncol, doublecomplex *M, doublecomplex *rhs )
{
    int k;
    doublecomplex x0, x1, x2, x3, temp;
    doublecomplex *M0;
    doublecomplex *Mki0, *Mki1, *Mki2, *Mki3;
    register int firstcol = 0;

    M0 = &M[0];


    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];
      	zz_mult(&temp, &x0, Mki0); Mki0++;
      	z_sub(&x1, &rhs[firstcol+1], &temp);
      	zz_mult(&temp, &x0, Mki0); Mki0++;
	z_sub(&x2, &rhs[firstcol+2], &temp);
	zz_mult(&temp, &x1, Mki1); Mki1++;
	z_sub(&x2, &x2, &temp);
      	zz_mult(&temp, &x0, Mki0); Mki0++;
	z_sub(&x3, &rhs[firstcol+3], &temp);
	zz_mult(&temp, &x1, Mki1); Mki1++;
	z_sub(&x3, &x3, &temp);
	zz_mult(&temp, &x2, Mki2); Mki2++;
	z_sub(&x3, &x3, &temp);

 	rhs[++firstcol] = x1;
      	rhs[++firstcol] = x2;
      	rhs[++firstcol] = x3;
      	++firstcol;
    
      	for (k = firstcol; k < ncol; k++) {
	    zz_mult(&temp, &x0, Mki0); Mki0++;
	    z_sub(&rhs[k], &rhs[k], &temp);
	    zz_mult(&temp, &x1, Mki1); Mki1++;
	    z_sub(&rhs[k], &rhs[k], &temp);
	    zz_mult(&temp, &x2, Mki2); Mki2++;
	    z_sub(&rhs[k], &rhs[k], &temp);
	    zz_mult(&temp, &x3, Mki3); Mki3++;
	    z_sub(&rhs[k], &rhs[k], &temp);
	}

        M0 += 4 * ldm + 4;
    }

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

        x0 = rhs[firstcol];
	zz_mult(&temp, &x0, Mki0); Mki0++;
	z_sub(&x1, &rhs[firstcol+1], &temp);

      	rhs[++firstcol] = x1;
      	++firstcol;
    
      	for (k = firstcol; k < ncol; k++) {
	    zz_mult(&temp, &x0, Mki0); Mki0++;
	    z_sub(&rhs[k], &rhs[k], &temp);
	    zz_mult(&temp, &x1, Mki1); Mki1++;
	    z_sub(&rhs[k], &rhs[k], &temp);
	} 
    }
    
}

/*
 * 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
zusolve ( ldm, ncol, M, rhs )
int ldm;	/* in */
int ncol;	/* in */
doublecomplex *M;	/* in */
doublecomplex *rhs;	/* modified */
{
    doublecomplex xj, temp;
    int jcol, j, irow;

    jcol = ncol - 1;

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

	z_div(&xj, &rhs[jcol], &M[jcol + jcol*ldm]); /* M(jcol, jcol) */
	rhs[jcol] = xj;
	
	for (irow = 0; irow < jcol; irow++) {
	    zz_mult(&temp, &xj, &M[irow+jcol*ldm]); /* M(irow, jcol) */
	    z_sub(&rhs[irow], &rhs[irow], &temp);
	}

	jcol--;

    }
}


/*
 * 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 zmatvec ( ldm, nrow, ncol, M, vec, Mxvec )
int ldm;	/* in -- leading dimension of M */
int nrow;	/* in */ 
int ncol;	/* in */
doublecomplex *M;	/* in */
doublecomplex *vec;	/* in */
doublecomplex *Mxvec;	/* in/out */
{
    doublecomplex vi0, vi1, vi2, vi3;
    doublecomplex *M0, temp;
    doublecomplex *Mki0, *Mki1, *Mki2, *Mki3;
    register int firstcol = 0;
    int k;

    M0 = &M[0];

    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++) {
	    zz_mult(&temp, &vi0, Mki0); Mki0++;
	    z_add(&Mxvec[k], &Mxvec[k], &temp);
	    zz_mult(&temp, &vi1, Mki1); Mki1++;
	    z_add(&Mxvec[k], &Mxvec[k], &temp);
	    zz_mult(&temp, &vi2, Mki2); Mki2++;
	    z_add(&Mxvec[k], &Mxvec[k], &temp);
	    zz_mult(&temp, &vi3, Mki3); Mki3++;
	    z_add(&Mxvec[k], &Mxvec[k], &temp);
	}

	M0 += 4 * ldm;
    }

    while ( firstcol < ncol ) {		/* Do 1 column */
 	Mki0 = M0;
	vi0 = vec[firstcol++];
	for (k = 0; k < nrow; k++) {
	    zz_mult(&temp, &vi0, Mki0); Mki0++;
	    z_add(&Mxvec[k], &Mxvec[k], &temp);
	}
	M0 += ldm;
    }
	
}

