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 )
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 ille
gal value
> 0: if INFO = i, the (i,i) element of the factor
U or L is zero, and the inverse could not be com
puted.
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