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NAME
     dpptri - 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 DPPTRF

SYNOPSIS
     SUBROUTINE DPPTRI( UPLO, N, AP, INFO )

     CHARACTER UPLO

     INTEGER INFO, N

     DOUBLE PRECISION AP( * )



     #include <sunperf.h>

     void dpptri(char uplo, int n, double *dap, int *info);

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.


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) 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 fol-
               lows:  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  (sym-
               metric) inverse of A, overwriting the input factor
               U or L.

     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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