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/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