
SPPTRI(l) ) SPPTRI(l)
NAME
SPPTRI  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 SPPTRF
SYNOPSIS
SUBROUTINE SPPTRI( UPLO, N, AP, INFO )
CHARACTER UPLO
INTEGER INFO, N
REAL AP( * )
PURPOSE
SPPTRI 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 SPPTRF.
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) REAL 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 jth column of U or L is
stored in the array AP as follows: if UPLO = 'U', AP(i + (j1)*j/2) = U(i,j) for
1<=i<=j; if UPLO = 'L', AP(i + (j1)*(2nj)/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 (output) INTEGER
= 0: successful exit
< 0: if INFO = i, the ith 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 version 3.0 15 June 2000 SPPTRI(l) 
