pdlaqgs.c File Reference

Equilibrates a general sparse M by N matrix. More...

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

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Macros
#define	THRESH   (0.1)

Functions
void	pdlaqgs (SuperMatrix *A, double *r, double *c, double rowcnd, double colcnd, double amax, char *equed)

Detailed Description

Equilibrates a general sparse M by N matrix.

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 name:  pdlaqgs.c
History:     Modified from LAPACK routine DLAQGE

Macro Definition Documentation

THRESH

#define THRESH   (0.1)

Function Documentation

pdlaqgs()

void pdlaqgs	(	SuperMatrix *	A,
		double *	r,
		double *	c,
		double	rowcnd,
		double	colcnd,
		double	amax,
		char *	equed
	)

    Purpose
    =======

    PDLAQGS equilibrates a general sparse M by N matrix A using the row
    and column 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_NR_loc; Dtype = SLU_D; Mtype = SLU_GE.

    R       (input) double*, dimension (A->nrow)
            The row scale factors for A.

    C       (input) double*, dimension (A->ncol)
            The column scale factors for A.

    ROWCND  (input) double
            Ratio of the smallest R(i) to the largest R(i).

    COLCND  (input) double
            Ratio of the smallest C(i) to the largest C(i).

    AMAX    (input) double
            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            = 'B':  Both row and column equilibration, i.e., A has been
                    replaced by diag(R) * A * diag(C).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.

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

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