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DLAQSY(1) LAPACK auxiliary routine (version 3.2) DLAQSY(1)

NAME

DLAQSY - equilibrates a symmetric matrix A using the scaling factors in the vector S

SYNOPSIS

UPLO, N, A, LDA, S, SCOND, AMAX, EQUED )

CHARACTER EQUED, UPLO INTEGER LDA, N DOUBLE PRECISION AMAX, SCOND DOUBLE PRECISION A( LDA, * ), S( * )

PURPOSE

DLAQSY equilibrates a symmetric matrix A using the scaling factors in the vector S.

ARGUMENTS

Specifies whether the upper or lower triangular part of the symmetric matrix A is stored. = 'U': Upper triangular
= 'L': Lower triangular
The order of the matrix A. N >= 0.
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).
The leading dimension of the array A. LDA >= max(N,1).
The scale factors for A.
Ratio of the smallest S(i) to the largest S(i).
Absolute value of largest matrix entry.
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= 'Y': Equilibration was done, i.e., A has been replaced by diag(S) * A * diag(S).

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.

November 2008 LAPACK auxiliary routine (version 3.2)