#include "stdafx.h"
/*
* -- SuperLU routine (version 2.0) --
* Lawrence Berkeley National Lab, Univ. of California Berkeley,
* and Xerox Palo Alto Research Center.
* September 10, 2007
*
*/
/*
* File name: slaqgs.c
* History: Modified from LAPACK routine SLAQGE
*/
#include <math.h>
#include "hnum_pssp_defs.h"
#ifdef small
#undef small
#endif
namespace harlinn
{
namespace numerics
{
namespace SuperLU
{
namespace Single
{
void
slaqgs(SuperMatrix *A, float *r, float *c,
float rowcnd, float colcnd, float amax, equed_t *equed)
{
/*
Purpose
=======
slaqgs() 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 = SLU_NC; Dtype = SLU_S; Mtype = SLU_GE.
R (input) float*, dimension (A->nrow)
The row scale factors for A.
C (input) float*, dimension (A->ncol)
The column scale factors for A.
ROWCND (input) float
Ratio of the smallest R(i) to the largest R(i).
COLCND (input) float
Ratio of the smallest C(i) to the largest C(i).
AMAX (input) float
Absolute value of largest matrix entry.
EQUED (output) equed_t*
Specifies the form of equilibration that was done.
= NOEQUIL: No equilibration
= ROW: Row equilibration, i.e., A has been premultiplied by
diag(R).
= COL: Column equilibration, i.e., A has been postmultiplied
by diag(C).
= BOTH: Both row and column equilibration, i.e., A has been
replaced by diag(R) * A * diag(C).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.
=====================================================================
*/
#define THRESH (0.1)
/* Local variables */
NCformat *Astore;
float *Aval;
int i, j, irow;
float large, small, cj;
/* Quick return if possible */
if (A->nrow <= 0 || A->ncol <= 0) {
*equed = NOEQUIL;
return;
}
Astore = (NCformat*)A->Store;
Aval = (float*)Astore->nzval;
/* Initialize LARGE and SMALL. */
small = slamch_("Safe minimum") / slamch_("Precision");
large = 1. / small;
if (rowcnd >= THRESH && amax >= small && amax <= large) {
if (colcnd >= THRESH)
*equed = NOEQUIL;
else {
/* Column scaling */
for (j = 0; j < A->ncol; ++j) {
cj = c[j];
for (i = Astore->colptr[j]; i < Astore->colptr[j+1]; ++i) {
Aval[i] *= cj;
}
}
*equed = COL;
}
} else if (colcnd >= THRESH) {
/* Row scaling, no column scaling */
for (j = 0; j < A->ncol; ++j)
for (i = Astore->colptr[j]; i < Astore->colptr[j+1]; ++i) {
irow = Astore->rowind[i];
Aval[i] *= r[irow];
}
*equed = ROW;
} else {
/* Row and column scaling */
for (j = 0; j < A->ncol; ++j) {
cj = c[j];
for (i = Astore->colptr[j]; i < Astore->colptr[j+1]; ++i) {
irow = Astore->rowind[i];
Aval[i] *= cj * r[irow];
}
}
*equed = BOTH;
}
return;
} /* slaqgs */
};
};
};
};