table of contents
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/sgeequ.f(3) | Library Functions Manual | /home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/sgeequ.f(3) |
NAME¶
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/sgeequ.f
SYNOPSIS¶
Functions/Subroutines¶
subroutine SGEEQU (m, n, a, lda, r, c, rowcnd, colcnd,
amax, info)
SGEEQU
Function/Subroutine Documentation¶
subroutine SGEEQU (integer m, integer n, real, dimension( lda, * ) a, integer lda, real, dimension( * ) r, real, dimension( * ) c, real rowcnd, real colcnd, real amax, integer info)¶
SGEEQU
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 !> 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. !>
Parameters
M
!> M is INTEGER !> The number of rows of the matrix A. M >= 0. !>
N
!> N is INTEGER !> The number of columns of the matrix A. N >= 0. !>
A
!> A is REAL array, dimension (LDA,N) !> The M-by-N matrix whose equilibration factors are !> to be computed. !>
LDA
!> LDA is INTEGER !> The leading dimension of the array A. LDA >= max(1,M). !>
R
!> R is REAL array, dimension (M) !> If INFO = 0 or INFO > M, R contains the row scale factors !> for A. !>
C
!> C is REAL array, dimension (N) !> If INFO = 0, C contains the column scale factors for A. !>
ROWCND
!> ROWCND is REAL !> 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
!> COLCND is REAL !> 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 scaling by C. !>
AMAX
!> AMAX is REAL !> Absolute value of largest matrix element. If AMAX is very !> close to overflow or very close to underflow, the matrix !> should be scaled. !>
INFO
!> INFO is INTEGER !> = 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 !>
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 137 of file sgeequ.f.
Author¶
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Version 3.12.0 | LAPACK |