SRC/claqgs.c File Reference

Equlibrates a general sprase matrix. More...

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

Defines
#define	THRESH   (0.1)
Functions
void	claqgs (SuperMatrix *A, float *r, float *c, float rowcnd, float colcnd, float amax, char *equed)

---

Detailed Description

 -- SuperLU routine (version 2.0) --
 Univ. of California Berkeley, Xerox Palo Alto Research Center,
 and Lawrence Berkeley National Lab.
 November 15, 1997

 Modified from LAPACK routine CLAQGE
 

---

Define Documentation

#define THRESH   (0.1)

---

Function Documentation

void claqgs	(	SuperMatrix *	A,
		float *	r,
		float *	c,
		float	rowcnd,
		float	colcnd,
		float	amax,
		char *	equed
	)

   Purpose   
   =======

   CLAQGS 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_C; Mtype = 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) 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           = 'B':  Both row and column equilibration, i.e., A has been
                   replaced by diag(R) * A * diag(C).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.

   =====================================================================