## SYNOPSIS

- SUBROUTINE PCDBTRF(
- N, BWL, BWU, A, JA, DESCA, AF, LAF, WORK, LWORK, INFO )

- INTEGER BWL, BWU, INFO, JA, LAF, LWORK, N

- INTEGER DESCA( * )

- COMPLEX A( * ), AF( * ), WORK( * )

## PURPOSE

PCDBTRF computes a LU factorization of an N-by-N complex banded diagonally dominant-like distributed matrix with bandwidth BWL, BWU: A(1:N, JA:JA+N-1). Reordering is used to increase parallelism in the factorization. This reordering results in factors that are DIFFERENT from those produced by equivalent sequential codes. These factors cannot be used directly by users; however, they can be used insubsequent calls to PCDBTRS to solve linear systems.

The factorization has the form

P A(1:N, JA:JA+N-1) P^T = L U

where U is a banded upper triangular matrix and L is banded
lower triangular, and P is a permutation matrix.