Provided by: liblapack-doc_3.3.1-1_all bug

NAME

       LAPACK-3  -  computes  the Cholesky factorization of a complex Hermitian positive definite
       matrix A stored in packed format

SYNOPSIS

       SUBROUTINE ZPPTRF( UPLO, N, AP, INFO )

           CHARACTER      UPLO

           INTEGER        INFO, N

           COMPLEX*16     AP( * )

PURPOSE

       ZPPTRF computes the Cholesky factorization of a complex Hermitian positive definite matrix
       A stored in packed format.
        The factorization has the form
           A = U**H * U,  if UPLO = 'U', or
           A = L  * L**H,  if UPLO = 'L',
        where U is an upper triangular matrix and L is lower triangular.

ARGUMENTS

        UPLO    (input) CHARACTER*1
                = 'U':  Upper triangle of A is stored;
                = 'L':  Lower triangle of A is stored.

        N       (input) INTEGER
                The order of the matrix A.  N >= 0.

        AP      (input/output) COMPLEX*16 array, dimension (N*(N+1)/2)
                On entry, the upper or lower triangle of the Hermitian matrix
                A, packed columnwise in a linear array.  The j-th column of A
                is stored in the array AP as follows:
                if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
                if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n.
                See below for further details.
                On exit, if INFO = 0, the triangular factor U or L from the
                Cholesky factorization A = U**H*U or A = L*L**H, in the same
                storage format as A.

        INFO    (output) INTEGER
                = 0:  successful exit
                < 0:  if INFO = -i, the i-th argument had an illegal value
                > 0:  if INFO = i, the leading minor of order i is not
                positive definite, and the factorization could not be
                completed.

FURTHER DETAILS

        The packed storage scheme is illustrated by the following example
        when N = 4, UPLO = 'U':
        Two-dimensional storage of the Hermitian matrix A:
           a11 a12 a13 a14
               a22 a23 a24
                   a33 a34     (aij = conjg(aji))
                       a44
        Packed storage of the upper triangle of A:
        AP = [ a11, a12, a22, a13, a23, a33, a14, a24, a34, a44 ]

 LAPACK routine (version 3.3.1)             April 2011                            ZPPTRF(3lapack)