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


SYNOPSIS

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

           CHARACTER      UPLO

           INTEGER        INFO, LDA, N

           COMPLEX        A( LDA, * )


PURPOSE

       CPOTRF 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  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 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 tri­
               angular 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

               > 0:  if INFO = i, the leading minor of order i is
               not positive definite, and the factorization could
               not be completed.


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