CPPTRI(1) LAPACK routine (version 3.2) CPPTRI(1)NAME
CPPTRI - computes the inverse of a complex Hermitian positive definite
matrix A using the Cholesky factorization A = U**H*U or A = L*L**H com‐
puted by CPPTRF
SYNOPSIS
SUBROUTINE CPPTRI( UPLO, N, AP, INFO )
CHARACTER UPLO
INTEGER INFO, N
COMPLEX AP( * )
PURPOSE
CPPTRI computes the inverse of a complex Hermitian positive definite
matrix A using the Cholesky factorization A = U**H*U or A = L*L**H com‐
puted by CPPTRF.
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 array, dimension (N*(N+1)/2)
On entry, the triangular factor U or L from the Cholesky fac‐
torization 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 follows: 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 (Hermit‐
ian) 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 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 routine (version 3.2) November 2008 CPPTRI(1)
