sgeequ (3p)

Name

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

Synopsis

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

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

SUBROUTINE SGEEQU_64(M, N, A, LDA, R, C, ROWCND, COLCND, AMAX,
INFO)

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




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

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

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

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




C INTERFACE
#include <sunperf.h>

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

void  sgeequ_64(long m, long n, float *a, long lda, float *r, float *c,
float *rowcnd, float *colcnd, float *amax, long *info);

Description

Oracle Solaris Studio Performance Library                           sgeequ(3P)



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


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

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

       SUBROUTINE SGEEQU_64(M, N, A, LDA, R, C, ROWCND, COLCND, AMAX,
             INFO)

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




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

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

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

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




   C INTERFACE
       #include <sunperf.h>

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

       void  sgeequ_64(long m, long n, float *a, long lda, float *r, float *c,
                 float *rowcnd, float *colcnd, float *amax, long *info);



PURPOSE
       sgeequ 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                        sgeequ(3P)