dlaqsp (l)  Linux Man Pages
dlaqsp: equilibrates a symmetric matrix A using the scaling factors in the vector S
NAME
DLAQSP  equilibrates a symmetric matrix A using the scaling factors in the vector SSYNOPSIS
 SUBROUTINE DLAQSP(
 UPLO, N, AP, S, SCOND, AMAX, EQUED )
 CHARACTER EQUED, UPLO
 INTEGER N
 DOUBLE PRECISION AMAX, SCOND
 DOUBLE PRECISION AP( * ), S( * )
PURPOSE
DLAQSP 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) DOUBLE PRECISION 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) DOUBLE PRECISION array, dimension (N)
 The scale factors for A.
 SCOND (input) DOUBLE PRECISION
 Ratio of the smallest S(i) to the largest S(i).
 AMAX (input) DOUBLE PRECISION
 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= aqYaq: Equilibration was done, i.e., A has been replaced by diag(S) * A * diag(S).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.