ZLAQHP(3F)ZLAQHP(3F)NAMEZLAQHP - equilibrate a Hermitian matrix A using the scaling factors in
the vector S
SYNOPSIS
SUBROUTINE ZLAQHP( UPLO, N, AP, S, SCOND, AMAX, EQUED )
CHARACTER EQUED, UPLO
INTEGER N
DOUBLE PRECISION AMAX, SCOND
DOUBLE PRECISION S( * )
COMPLEX*16 AP( * )
PURPOSEZLAQHP equilibrates a Hermitian 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
Hermitian matrix A is stored. = 'U': Upper triangular
= 'L': Lower triangular
N (input) INTEGER
The order of the matrix A. N >= 0.
AP (input/output) COMPLEX*16 array, dimension (N*(N+1)/2)
On entry, the upper or lower triangle of the Hermitian 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) 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.
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ZLAQHP(3F)ZLAQHP(3F)
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= 'Y': Equilibration was done, i.e., A has been replaced by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.
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