dgeequ (3p)

Name

dgeequ - by-N matrix A and reduce its condition number

Synopsis

SUBROUTINE DGEEQU(M, N, A, LDA, R, C, ROWCND, COLCND, AMAX,
INFO)

INTEGER M, N, LDA, INFO
DOUBLE PRECISION ROWCND, COLCND, AMAX
DOUBLE PRECISION A(LDA,*), R(*), C(*)

SUBROUTINE DGEEQU_64(M, N, A, LDA, R, C, ROWCND, COLCND, AMAX,
INFO)

INTEGER*8 M, N, LDA, INFO
DOUBLE PRECISION ROWCND, COLCND, AMAX
DOUBLE PRECISION A(LDA,*), R(*), C(*)




F95 INTERFACE
SUBROUTINE GEEQU(M, N, A, LDA, R, C, ROWCND, COLCND,
AMAX, INFO)

INTEGER :: M, N, LDA, INFO
REAL(8) :: ROWCND, COLCND, AMAX
REAL(8), DIMENSION(:) :: R, C
REAL(8), DIMENSION(:,:) :: A

SUBROUTINE GEEQU_64(M, N, A, LDA, R, C, ROWCND, COLCND,
AMAX, INFO)

INTEGER(8) :: M, N, LDA, INFO
REAL(8) :: ROWCND, COLCND, AMAX
REAL(8), DIMENSION(:) :: R, C
REAL(8), DIMENSION(:,:) :: A




C INTERFACE
#include <sunperf.h>

void dgeequ(int m, int n, double *a, int lda,  double  *r,  double  *c,
double *rowcnd, double *colcnd, double *amax, int *info);

void  dgeequ_64(long  m, long n, double *a, long lda, double *r, double
*c,  double  *rowcnd,  double  *colcnd,  double  *amax,  long
*info);

Description

Oracle Solaris Studio Performance Library                           dgeequ(3P)



NAME
       dgeequ  - compute row and column scalings intended to equilibrate an M-
       by-N matrix A and reduce its condition number


SYNOPSIS
       SUBROUTINE DGEEQU(M, N, A, LDA, R, C, ROWCND, COLCND, AMAX,
             INFO)

       INTEGER M, N, LDA, INFO
       DOUBLE PRECISION ROWCND, COLCND, AMAX
       DOUBLE PRECISION A(LDA,*), R(*), C(*)

       SUBROUTINE DGEEQU_64(M, N, A, LDA, R, C, ROWCND, COLCND, AMAX,
             INFO)

       INTEGER*8 M, N, LDA, INFO
       DOUBLE PRECISION ROWCND, COLCND, AMAX
       DOUBLE PRECISION A(LDA,*), R(*), C(*)




   F95 INTERFACE
       SUBROUTINE GEEQU(M, N, A, LDA, R, C, ROWCND, COLCND,
              AMAX, INFO)

       INTEGER :: M, N, LDA, INFO
       REAL(8) :: ROWCND, COLCND, AMAX
       REAL(8), DIMENSION(:) :: R, C
       REAL(8), DIMENSION(:,:) :: A

       SUBROUTINE GEEQU_64(M, N, A, LDA, R, C, ROWCND, COLCND,
              AMAX, INFO)

       INTEGER(8) :: M, N, LDA, INFO
       REAL(8) :: ROWCND, COLCND, AMAX
       REAL(8), DIMENSION(:) :: R, C
       REAL(8), DIMENSION(:,:) :: A




   C INTERFACE
       #include <sunperf.h>

       void dgeequ(int m, int n, double *a, int lda,  double  *r,  double  *c,
                 double *rowcnd, double *colcnd, double *amax, int *info);

       void  dgeequ_64(long  m, long n, double *a, long lda, double *r, double
                 *c,  double  *rowcnd,  double  *colcnd,  double  *amax,  long
                 *info);



PURPOSE
       dgeequ  computes  row and column scalings intended to equilibrate an M-
       by-N matrix A and reduce its condition number.  R returns the row scale
       factors  and  C  the  column  scale  factors, chosen to try to make the
       largest element in each row and column of the matrix  B  with  elements
       B(i,j)=R(i)*A(i,j)*C(j) have absolute value 1.

       R(i)  and C(j) are restricted to be between SMLNUM = smallest safe num-
       ber and BIGNUM = largest safe number.  Use of these scaling factors  is
       not  guaranteed  to  reduce the condition number of A but works well in
       practice.


ARGUMENTS
       M (input) The number of rows of the matrix A.  M >= 0.


       N (input) The number of columns of the matrix A.  N >= 0.


       A (input) The M-by-N matrix whose equilibration factors are to be  com-
                 puted.


       LDA (input)
                 The leading dimension of the array A.  LDA >= max(1,M).


       R (output)
                 If INFO = 0 or INFO > M, R contains the row scale factors for
                 A.


       C (output)
                 If INFO = 0,  C contains the column scale factors for A.


       ROWCND (output)
                 If INFO = 0 or INFO > M, ROWCND contains  the  ratio  of  the
                 smallest R(i) to the largest R(i).  If ROWCND >= 0.1 and AMAX
                 is neither too large nor too small, it is not  worth  scaling
                 by R.


       COLCND (output)
                 If  INFO  = 0, COLCND contains the ratio of the smallest C(i)
                 to the largest C(i).  If COLCND >= 0.1, it is not worth scal-
                 ing by C.


       AMAX (output)
                 Absolute  value  of  largest matrix element.  If AMAX is very
                 close to overflow or very  close  to  underflow,  the  matrix
                 should be scaled.


       INFO (output)
                 = 0:  successful exit
                 < 0:  if INFO = -i, the i-th argument had an illegal value
                 > 0:  if INFO = i,  and i is
                 <= M:  the i-th row of A is exactly zero
                 >  M:  the (i-M)-th column of A is exactly zero




                                  7 Nov 2015                        dgeequ(3P)