zgeequ
zgeequ - compute row and column scalings intended to equilibrate an M-by-N matrix A and reduce its condition number
SUBROUTINE ZGEEQU( M, N, A, LDA, ROWSC, COLSC, ROWCN, COLCN, AMAX,
* INFO)
DOUBLE COMPLEX A(LDA,*)
INTEGER M, N, LDA, INFO
DOUBLE PRECISION ROWCN, COLCN, AMAX
DOUBLE PRECISION ROWSC(*), COLSC(*)
SUBROUTINE ZGEEQU_64( M, N, A, LDA, ROWSC, COLSC, ROWCN, COLCN,
* AMAX, INFO)
DOUBLE COMPLEX A(LDA,*)
INTEGER*8 M, N, LDA, INFO
DOUBLE PRECISION ROWCN, COLCN, AMAX
DOUBLE PRECISION ROWSC(*), COLSC(*)
SUBROUTINE GEEQU( [M], [N], A, [LDA], ROWSC, COLSC, ROWCN, COLCN,
* AMAX, [INFO])
COMPLEX(8), DIMENSION(:,:) :: A
INTEGER :: M, N, LDA, INFO
REAL(8) :: ROWCN, COLCN, AMAX
REAL(8), DIMENSION(:) :: ROWSC, COLSC
SUBROUTINE GEEQU_64( [M], [N], A, [LDA], ROWSC, COLSC, ROWCN, COLCN,
* AMAX, [INFO])
COMPLEX(8), DIMENSION(:,:) :: A
INTEGER(8) :: M, N, LDA, INFO
REAL(8) :: ROWCN, COLCN, AMAX
REAL(8), DIMENSION(:) :: ROWSC, COLSC
#include <sunperf.h>
void zgeequ(int m, int n, doublecomplex *a, int lda, double *rowsc, double *colsc, double *rowcn, double *colcn, double *amax, int *info);
void zgeequ_64(long m, long n, doublecomplex *a, long lda, double *rowsc, double *colsc, double *rowcn, double *colcn, double *amax, long *info);
zgeequ 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
number 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.
-
* M (input)
-
The number of rows of the matrix A. M >= 0.
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* N (input)
-
The number of columns of the matrix A. N >= 0.
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* A (input)
-
The M-by-N matrix whose equilibration factors are
to be computed.
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* LDA (input)
-
The leading dimension of the array A. LDA >= max(1,M).
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* ROWSC (output)
-
If INFO = 0 or INFO > M, ROWSC contains the row scale factors
for A.
-
* COLSC (output)
-
If INFO = 0, COLSC contains the column scale factors for A.
-
* ROWCN (output)
-
If INFO = 0 or INFO > M, ROWCN contains the ratio of the
smallest ROWSC(i) to the largest ROWSC(i). If ROWCN >= 0.1 and
AMAX is neither too large nor too small, it is not worth
scaling by ROWSC.
-
* COLCN (output)
-
If INFO = 0, COLCN contains the ratio of the smallest
COLSC(i) to the largest COLSC(i). If COLCN >= 0.1, it is not
worth scaling by COLSC.
-
* 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)
-