# dpptri.f - Man Page

SRC/dpptri.f

## Synopsis

### Functions/Subroutines

subroutine dpptri (uplo, n, ap, info)
DPPTRI

## Function/Subroutine Documentation

### subroutine dpptri (character uplo, integer n, double precision, dimension( * ) ap, integer info)

DPPTRI

Purpose:

``` DPPTRI computes the inverse of a real symmetric positive definite
matrix A using the Cholesky factorization A = U**T*U or A = L*L**T
computed by DPPTRF.```
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 DOUBLE PRECISION array, dimension (N*(N+1)/2)
On entry, the triangular factor U or L from the Cholesky
factorization A = U**T*U or A = L*L**T, 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 (symmetric)
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

NAG Ltd.

Definition at line 92 of file dpptri.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page dpptri(3) is an alias of dpptri.f(3).

Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK