Contents
zpocon - estimate the reciprocal of the condition number (in
the 1-norm) of a complex Hermitian positive definite matrix
using the Cholesky factorization A = U**H*U or A = L*L**H
computed by ZPOTRF
SUBROUTINE ZPOCON(UPLO, N, A, LDA, ANORM, RCOND, WORK, WORK2, INFO)
CHARACTER * 1 UPLO
DOUBLE COMPLEX A(LDA,*), WORK(*)
INTEGER N, LDA, INFO
DOUBLE PRECISION ANORM, RCOND
DOUBLE PRECISION WORK2(*)
SUBROUTINE ZPOCON_64(UPLO, N, A, LDA, ANORM, RCOND, WORK, WORK2,
INFO)
CHARACTER * 1 UPLO
DOUBLE COMPLEX A(LDA,*), WORK(*)
INTEGER*8 N, LDA, INFO
DOUBLE PRECISION ANORM, RCOND
DOUBLE PRECISION WORK2(*)
F95 INTERFACE
SUBROUTINE POCON(UPLO, [N], A, [LDA], ANORM, RCOND, [WORK], [WORK2],
[INFO])
CHARACTER(LEN=1) :: UPLO
COMPLEX(8), DIMENSION(:) :: WORK
COMPLEX(8), DIMENSION(:,:) :: A
INTEGER :: N, LDA, INFO
REAL(8) :: ANORM, RCOND
REAL(8), DIMENSION(:) :: WORK2
SUBROUTINE POCON_64(UPLO, [N], A, [LDA], ANORM, RCOND, [WORK], [WORK2],
[INFO])
CHARACTER(LEN=1) :: UPLO
COMPLEX(8), DIMENSION(:) :: WORK
COMPLEX(8), DIMENSION(:,:) :: A
INTEGER(8) :: N, LDA, INFO
REAL(8) :: ANORM, RCOND
REAL(8), DIMENSION(:) :: WORK2
C INTERFACE
#include <sunperf.h>
void zpocon(char uplo, int n, doublecomplex *a, int lda,
double anorm, double *rcond, int *info);
void zpocon_64(char uplo, long n, doublecomplex *a, long
lda, double anorm, double *rcond, long *info);
zpocon estimates the reciprocal of the condition number (in
the 1-norm) of a complex Hermitian positive definite matrix
using the Cholesky factorization A = U**H*U or A = L*L**H
computed by ZPOTRF.
An estimate is obtained for norm(inv(A)), and the reciprocal
of the condition number is computed as RCOND = 1 / (ANORM *
norm(inv(A))).
UPLO (input)
= 'U': Upper triangle of A is stored;
= 'L': Lower triangle of A is stored.
N (input) The order of the matrix A. N >= 0.
A (input) The triangular factor U or L from the Cholesky
factorization A = U**H*U or A = L*L**H, as com-
puted by ZPOTRF.
LDA (input)
The leading dimension of the array A. LDA >=
max(1,N).
ANORM (input)
The 1-norm (or infinity-norm) of the Hermitian
matrix A.
RCOND (output)
The reciprocal of the condition number of the
matrix A, computed as RCOND = 1/(ANORM * AINVNM),
where AINVNM is an estimate of the 1-norm of
inv(A) computed in this routine.
WORK (workspace)
dimension(2*N)
WORK2 (workspace)
dimension(N)
INFO (output)
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an ille-
gal value