slaqsy()

subroutine slaqsy	(	character	uplo,
		integer	n,
		real, dimension( lda, * )	a,
		integer	lda,
		real, dimension( * )	s,
		real	scond,
		real	amax,
		character	equed )

SLAQSY scales a symmetric/Hermitian matrix, using scaling factors computed by spoequ.

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Purpose:

!>
!> SLAQSY equilibrates a symmetric matrix A using the scaling factors
!> in the vector S.
!> 

Parameters

[in]	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 !>
[in]	N	!> N is INTEGER !> The order of the matrix A. N >= 0. !>
[in,out]	A	!> A is REAL 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). !>
[in]	LDA	!> LDA is INTEGER !> The leading dimension of the array A. LDA >= max(N,1). !>
[in]	S	!> S is REAL array, dimension (N) !> The scale factors for A. !>
[in]	SCOND	!> SCOND is REAL !> Ratio of the smallest S(i) to the largest S(i). !>
[in]	AMAX	!> AMAX is REAL !> Absolute value of largest matrix entry. !>
[out]	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 = 'Y': Equilibration was done, i.e., A has been replaced by !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.