
ZPPTRI(l) ) ZPPTRI(l)
NAME
ZPPTRI  compute the inverse of a complex Hermitian positive 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 positive 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 jth column of U or L is
stored in the array AP as follows: if UPLO = 'U', AP(i + (j1)*j/2) = U(i,j) for
1<=i<=j; if UPLO = 'L', AP(i + (j1)*(2nj)/2) = L(i,j) for j<=i<=n.
On exit, the upper or lower triangle of the (Hermitian) inverse of A, overwriting
the input factor U or L.
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = i, the ith argument had an illegal value
> 0: if INFO = i, the (i,i) element of the factor U or L is zero, and the inverse
could not be computed.
LAPACK version 3.0 15 June 2000 ZPPTRI(l) 
