NAME

       CDTTRF  - compute an LU factorization of a complex tridiagonal matrix A using elimination without partial
       pivoting

SYNOPSIS

       SUBROUTINE CDTTRF( N, DL, D, DU, INFO )

           INTEGER        INFO, N

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

PURPOSE

       CDTTRF computes an LU factorization of a complex tridiagonal matrix A using elimination  without  partial
       pivoting.

       The factorization has the form
          A = L * U
       where L is a product of unit lower bidiagonal
       matrices and U is upper triangular with nonzeros in only the main diagonal and first superdiagonal.

ARGUMENTS

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

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

       INFO    (output) INTEGER
               = 0:  successful exit
               < 0:  if INFO = -i, the i-th argument had an illegal value
               > 0:  if INFO = i, U(i,i) 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.