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.

UPLO

          UPLO is CHARACTER*1


          = 'U':  Upper triangle of A is stored;


          = 'L':  Lower triangle of A is stored.

N

          N is INTEGER


          The order of the matrix A.  N >= 0.

A

          A is 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

          LDA is INTEGER


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

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.

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

November 2011