!>
!> 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.
!> 

UPLO

!>          UPLO is CHARACTER*1
!>          = 'U':  Upper triangular factor is stored in AP;
!>          = 'L':  Lower triangular factor is stored in AP.
!> 

N

!>          N is INTEGER
!>          The order of the matrix A.  N >= 0.
!> 

AP

!>          AP is 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 follows:
!>          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 (symmetric)
!>          inverse of A, overwriting the input factor U or L.
!> 

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.
!> 

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