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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