# CPPTRI (3) - Linux Manuals

cpptri.f -

## SYNOPSIS

### Functions/Subroutines

subroutine cpptri (UPLO, N, AP, INFO)
CPPTRI

## Function/Subroutine Documentation

### subroutine cpptri (characterUPLO, integerN, complex, dimension( * )AP, integerINFO)

CPPTRI

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
computed by CPPTRF.
```

Parameters:

UPLO

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

N

```          N is INTEGER
The order of the matrix A.  N >= 0.
```

AP

```          AP is COMPLEX 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 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 (Hermitian)
inverse of A, overwriting the input factor U or L.
```

INFO

```          INFO is 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.
```

Author:

Univ. of Tennessee

Univ. of California Berkeley