table of contents
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/dlaqsy.f(3) | Library Functions Manual | /home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/dlaqsy.f(3) |
NAME¶
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/dlaqsy.f
SYNOPSIS¶
Functions/Subroutines¶
subroutine DLAQSY (uplo, n, a, lda, s, scond, amax, equed)
DLAQSY scales a symmetric/Hermitian matrix, using scaling factors
computed by spoequ.
Function/Subroutine Documentation¶
subroutine DLAQSY (character uplo, integer n, double precision, dimension( lda, * ) a, integer lda, double precision, dimension( * ) s, double precision scond, double precision amax, character equed)¶
DLAQSY scales a symmetric/Hermitian matrix, using scaling factors computed by spoequ.
Purpose:
!> !> DLAQSY equilibrates a symmetric matrix A using the scaling factors !> in the vector S. !>
Parameters
UPLO
!> UPLO is CHARACTER*1 !> Specifies whether the upper or lower triangular part of the !> symmetric matrix A is stored. !> = 'U': Upper triangular !> = 'L': Lower triangular !>
N
!> N is INTEGER !> The order of the matrix A. N >= 0. !>
A
!> A is DOUBLE PRECISION array, dimension (LDA,N) !> On entry, the symmetric matrix A. If UPLO = 'U', the leading !> n by n upper triangular part of A contains the upper !> triangular part of the matrix A, and the strictly lower !> triangular part of A is not referenced. If UPLO = 'L', the !> leading n by n lower triangular part of A contains the lower !> triangular part of the matrix A, and the strictly upper !> triangular part of A is not referenced. !> !> On exit, if EQUED = 'Y', the equilibrated matrix: !> diag(S) * A * diag(S). !>
LDA
!> LDA is INTEGER !> The leading dimension of the array A. LDA >= max(N,1). !>
S
!> S is DOUBLE PRECISION array, dimension (N) !> The scale factors for A. !>
SCOND
!> SCOND is DOUBLE PRECISION !> Ratio of the smallest S(i) to the largest S(i). !>
AMAX
!> AMAX is DOUBLE PRECISION !> Absolute value of largest matrix entry. !>
EQUED
!> EQUED is CHARACTER*1 !> Specifies whether or not equilibration was done. !> = 'N': No equilibration. !> = 'Y': Equilibration was done, i.e., A has been replaced by !> diag(S) * A * diag(S). !>
Internal Parameters:
!> THRESH is a threshold value used to decide if scaling should be done !> based on the ratio of the scaling factors. If SCOND < THRESH, !> scaling is done. !> !> LARGE and SMALL are threshold values used to decide if scaling should !> be done based on the absolute size of the largest matrix element. !> If AMAX > LARGE or AMAX < SMALL, scaling is done. !>
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 132 of file dlaqsy.f.
Author¶
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