Provided by: scalapack-doc_1.5-10_all #### NAME

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

```

#### SYNOPSIS

```       SUBROUTINE ZDTTRF( N, DL, D, DU, INFO )

INTEGER        INFO, N

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

```

#### PURPOSE

```       ZDTTRF 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.
```