NAME

spotri - compute 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 SPOTRF

SYNOPSIS

SUBROUTINE SPOTRI(
UPLO, N, A, LDA, INFO )

void spotri(char uplo, long int n, float ∗sa, long int lda,
long int ∗info)

CHARACTER UPLO

INTEGER INFO, LDA, N

REAL A( LDA, ∗ )

PURPOSE

SPOTRI 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 SPOTRF. 
 

ARGUMENTS

UPLO    (input) CHARACTER∗1
= ’U’:  Upper triangle of A is stored;
= ’L’:  Lower triangle of A is stored.

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

A       (input/output) REAL array, dimension (LDA,N)
On entry, the triangular factor U or L from the Cholesky factorization A = U∗∗T∗U or A = L∗L∗∗T, as computed by SPOTRF. On exit, the upper or lower triangle of the (symmetric) inverse of A, overwriting the input factor U or L.

LDA     (input) INTEGER
The leading dimension of the array A.  LDA >= max(1,N).

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.

Sun, Inc.  —  Last change: 20 Sep 1996