dlaqgs.c File Reference

Equlibrates a general sprase matrix. More...

`#include <math.h>`
`#include "slu_ddefs.h"`
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## Macros

#define | THRESH (0.1)

## Functions

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

## Detailed Description

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.

    – 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 DLAQGE

## Macro Definition Documentation

#define THRESH (0.1)

## Function Documentation

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

#

    Purpose

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              = 'B':  Both row and column equilibration, i.e., A has been
                      replaced by diag(R) * A * diag(C).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