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# zpotrf

```
NAME
ZPOTRF - compute the Cholesky factorization of a complex
Hermitian positive definite matrix A

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

CHARACTER      UPLO

INTEGER        INFO, LDA, N

COMPLEX*16     A( LDA, * )

PURPOSE
ZPOTRF computes the Cholesky factorization of a complex Her-
mitian 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 tri-
angular.

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 con-
tains 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 tri-
angular 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.
```