subroutine claqsp (UPLO, N, AP, S, SCOND, AMAX, EQUED)
CLAQSP scales a symmetric/Hermitian matrix in packed storage, using scaling factors computed by sppequ.
CLAQSP scales a symmetric/Hermitian matrix in packed storage, using scaling factors computed by sppequ.
Purpose:
CLAQSP equilibrates a symmetric matrix A using the scaling factors in the vector S.
Parameters:
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 COMPLEX 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 = 'Y': Equilibration was done, i.e., A has been replaced by diag(S) * A * diag(S).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 California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
Definition at line 128 of file claqsp.f.
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