SRC/zgttrf.f(3)

NAME
SRC/zgttrf.f

SYNOPSIS

  Functions/Subroutines
subroutine zgttrf (n, dl, d, du, du2, ipiv, info)
ZGTTRF

Function/Subroutine Documentation

  subroutine zgttrf (integer n, complex*16, dimension( * ) dl, complex*16, dimension( * ) d, complex*16, dimension( * ) du, complex*16, dimension( * ) du2, integer, dimension( * ) ipiv, integer info)

ZGTTRF

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.
    !>

Parameters
    N

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

    DL

    !>          DL is 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

    !>          D is 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

    !>          DU is 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

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

    IPIV

    !>          IPIV is 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

    !>          INFO is 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.
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 123 of file zgttrf.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.