claqsp-f(3)

claqsp.f –

Synopsis

Functions/Subroutines

subroutine claqsp (UPLO, N, AP, S, SCOND, AMAX, EQUED)
CLAQSP scales a symmetric/Hermitian matrix in packed storage, using scaling factors computed by sppequ.

Function/Subroutine Documentation

subroutine claqsp (characterUPLO, integerN, complex, dimension( * )AP, real, dimension( * )S, realSCOND, realAMAX, characterEQUED)

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

 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 is INTEGER
 The order of the matrix A. N >= 0.

 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 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 = 'Y': Equilibration was done, i.e., A has been replaced by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 127 of file claqsp.f.

Author

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