slaqsp(l) [redhat man page]
SLAQSP(l) ) SLAQSP(l) NAME
SLAQSP - equilibrate a symmetric matrix A using the scaling factors in the vector S SYNOPSIS
SUBROUTINE SLAQSP( UPLO, N, AP, S, SCOND, AMAX, EQUED ) CHARACTER EQUED, UPLO INTEGER N REAL AMAX, SCOND REAL AP( * ), S( * ) PURPOSE
SLAQSP equilibrates a symmetric matrix A using the scaling factors in the vector S. ARGUMENTS
UPLO (input) CHARACTER*1 Specifies whether the upper or lower triangular part of the symmetric matrix A is stored. = 'U': Upper triangular = 'L': Lower triangular N (input) INTEGER The order of the matrix A. N >= 0. AP (input/output) REAL array, dimension (N*(N+1)/2) On entry, the upper or lower triangle of the symmetric matrix A, packed columnwise in a linear array. The j-th column of A is stored in the array AP as follows: if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j; if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n. On exit, the equilibrated matrix: diag(S) * A * diag(S), in the same storage format as A. S (input) REAL array, dimension (N) The scale factors for A. SCOND (input) REAL Ratio of the smallest S(i) to the largest S(i). AMAX (input) REAL Absolute value of largest matrix entry. EQUED (output) 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 = 'Y': Equilibration was done, i.e., A has been replaced by diag(S) * A * diag(S). 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. LAPACK version 3.0 15 June 2000 SLAQSP(l)
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slaqsp.f(3) LAPACK slaqsp.f(3) NAME
slaqsp.f - SYNOPSIS
Functions/Subroutines subroutine slaqsp (UPLO, N, AP, S, SCOND, AMAX, EQUED) SLAQSP scales a symmetric/Hermitian matrix in packed storage, using scaling factors computed by sppequ. Function/Subroutine Documentation subroutine slaqsp (characterUPLO, integerN, real, dimension( * )AP, real, dimension( * )S, realSCOND, realAMAX, characterEQUED) SLAQSP scales a symmetric/Hermitian matrix in packed storage, using scaling factors computed by sppequ. Purpose: SLAQSP 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. AP AP is REAL array, dimension (N*(N+1)/2) On entry, the upper or lower triangle of the symmetric matrix A, packed columnwise in a linear array. The j-th column of A is stored in the array AP as follows: if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j; if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n. On exit, the equilibrated matrix: diag(S) * A * diag(S), in the same storage format as A. S S is REAL array, dimension (N) The scale factors for A. SCOND SCOND is REAL Ratio of the smallest S(i) to the largest S(i). AMAX AMAX is REAL 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. Date: September 2012 Definition at line 126 of file slaqsp.f. Author Generated automatically by Doxygen for LAPACK from the source code. Version 3.4.2 Tue Sep 25 2012 slaqsp.f(3)