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

NAME

       LAPACK-3  -  computes  an  LU  factorization  of  a  complex  tridiagonal  matrix  A using
       elimination with partial pivoting and row interchanges

SYNOPSIS

       SUBROUTINE ZGTTRF( N, DL, D, DU, DU2, IPIV, INFO )

           INTEGER        INFO, N

           INTEGER        IPIV( * )

           COMPLEX*16     D( * ), DL( * ), DU( * ), DU2( * )

PURPOSE

       ZGTTRF computes an LU factorization of a complex tridiagonal matrix  A  using  elimination
       with partial pivoting and row interchanges.
        The factorization has the form
           A = L * U
        where L is a product of permutation and unit lower bidiagonal
        matrices and U is upper triangular with nonzeros in only the main
        diagonal and first two superdiagonals.

ARGUMENTS

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

        DL      (input/output) COMPLEX*16 array, dimension (N-1)
                On entry, DL must contain the (n-1) sub-diagonal elements of
                A.
                On exit, DL is overwritten by the (n-1) multipliers that
                define the matrix L from the LU factorization of A.

        D       (input/output) COMPLEX*16 array, dimension (N)
                On entry, D must contain the diagonal elements of A.
                On exit, D is overwritten by the n diagonal elements of the
                upper triangular matrix U from the LU factorization of A.

        DU      (input/output) COMPLEX*16 array, dimension (N-1)
                On entry, DU must contain the (n-1) super-diagonal elements
                of A.
                On exit, DU is overwritten by the (n-1) elements of the first
                super-diagonal of U.

        DU2     (output) COMPLEX*16 array, dimension (N-2)
                On exit, DU2 is overwritten by the (n-2) elements of the
                second super-diagonal of U.

        IPIV    (output) INTEGER array, dimension (N)
                The pivot indices; for 1 <= i <= n, row i of the matrix was
                interchanged with row IPIV(i).  IPIV(i) will always be either
                i or i+1; IPIV(i) = i indicates a row interchange was not
                required.

        INFO    (output) INTEGER
                = 0:  successful exit
                < 0:  if INFO = -k, the k-th argument had an illegal value
                > 0:  if INFO = k, U(k,k) is exactly zero. The factorization
                has been completed, but the factor U is exactly
                singular, and division by zero will occur if it is used
                to solve a system of equations.

 LAPACK routine (version 3.2)               April 2011                            ZGTTRF(3lapack)