slaqsp (l)  Linux Manuals
slaqsp: equilibrates a symmetric matrix A using the scaling factors in the vector S
NAME
SLAQSP  equilibrates a symmetric matrix A using the scaling factors in the vector SSYNOPSIS
 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.
= aqUaq: Upper triangular
= aqLaq: 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 jth column of A is stored in the array AP as follows: if UPLO = aqUaq, AP(i + (j1)*j/2) = A(i,j) for 1<=i<=j; if UPLO = aqLaq, AP(i + (j1)*(2nj)/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.
= aqNaq: No equilibration.
= aqYaq: Equilibration was done, i.e., A has been replaced by diag(S) * A * diag(S).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.