SRC/spptri.f(3)

NAME
SRC/spptri.f

SYNOPSIS

  Functions/Subroutines
subroutine spptri (uplo, n, ap, info)
SPPTRI

Function/Subroutine Documentation

  subroutine spptri (character uplo, integer n, real, dimension( * ) ap, integer info)

SPPTRI

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.

Parameters
    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 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 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.

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 92 of file spptri.f.

Author

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