ZPPTRI  - compute the inverse of a complex Hermitian posi­
       tive definite matrix A using the Cholesky factorization  A
       = U**H*U or A = L*L**H computed by ZPPTRF


SYNOPSIS

       SUBROUTINE ZPPTRI( UPLO, N, AP, INFO )

           CHARACTER      UPLO

           INTEGER        INFO, N

           COMPLEX*16     AP( * )


PURPOSE

       ZPPTRI  computes  the inverse of a complex Hermitian posi­
       tive definite matrix A using the Cholesky factorization  A
       = U**H*U or A = L*L**H computed by ZPPTRF.


ARGUMENTS

       UPLO    (input) CHARACTER*1
               = 'U':  Upper triangular factor is stored in AP;
               = 'L':  Lower triangular factor is stored in AP.

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

       AP      (input/output) COMPLEX*16 array, dimension
               (N*(N+1)/2)
               On entry, the triangular factor U or  L  from  the
               Cholesky  factorization  A = U**H*U or A = L*L**H,
               packed columnwise as a  linear  array.   The  j-th
               column of U or L is stored in the array AP as fol­
               lows: if UPLO = 'U', AP(i +  (j-1)*j/2)  =  U(i,j)
               for 1<=i<=j; if UPLO = 'L', AP(i + (j-1)*(2n-j)/2)
               = L(i,j) for j<=i<=n.

               On exit, the upper or lower triangle of the  (Her­
               mitian) inverse of A, overwriting the input factor
               U or L.

       INFO    (output) INTEGER
               = 0:  successful exit
               < 0:  if INFO = -i, the i-th argument had an ille­
               gal value
               > 0:  if INFO = i, the (i,i) element of the factor
               U or L is zero, and the inverse could not be  com­
               puted.


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