NAME

zpotrf - compute the Cholesky factorization of a complex Hermitian positive definite matrix A

SYNOPSIS

SUBROUTINE ZPOTRF(
UPLO, N, A, LDA, INFO )

void zpotrf(char uplo, long int n, doublecomplex ∗za,
long int lda, long int ∗info)

CHARACTER UPLO

INTEGER INFO, LDA, N

COMPLEX∗16 A( LDA, ∗ )

PURPOSE

ZPOTRF computes the Cholesky factorization of a complex Hermitian positive definite matrix A. 
 
The factorization has the form
   A = U∗∗H ∗ U,  if UPLO = ’U’, or
   A = L  ∗ L∗∗H,  if UPLO = ’L’,
where U is an upper triangular matrix and L is lower triangular.
 
This is the block version of the algorithm, calling Level 3 BLAS.
 

ARGUMENTS

UPLO    (input) CHARACTER∗1
= ’U’:  Upper triangle of A is stored;
= ’L’:  Lower triangle of A is stored.

N       (input) INTEGER
The order of the matrix A.  N >= 0.

A       (input/output) COMPLEX∗16 array, dimension (LDA,N)
On entry, the Hermitian matrix A.  If UPLO = ’U’, the leading N-by-N upper triangular part of A contains the upper triangular part of the matrix A, and the strictly lower triangular part of A is not referenced.  If UPLO = ’L’, the leading N-by-N lower triangular part of A contains the lower triangular part of the matrix A, and the strictly upper triangular part of A is not referenced.
 
On exit, if INFO = 0, the factor U or L from the Cholesky factorization A = U∗∗H∗U or A = L∗L∗∗H.

LDA     (input) INTEGER
The leading dimension of the array A.  LDA >= max(1,N).

INFO    (output) INTEGER
= 0:  successful exit
< 0:  if INFO = -i, the i-th argument had an illegal value
> 0:  if INFO = i, the leading minor of order i is not positive definite, and the factorization could not be completed.

Sun, Inc.  —  Last change: 20 Sep 1996