NAME

       PCGBTRF  -  compute a LU factorization of an N-by-N complex banded distributed matrix with bandwidth BWL,
       BWU

SYNOPSIS

       SUBROUTINE PCGBTRF( N, BWL, BWU, A, JA, DESCA, IPIV, AF, LAF, WORK, LWORK, INFO )

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

           INTEGER         DESCA( * ), IPIV( * )

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

PURPOSE

       PCGBTRF computes a LU factorization of an N-by-N complex banded 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 in
       subsequent calls to PCGBTRS to solve linear systems.

       The factorization has the form

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

       where U is a banded upper triangular matrix and L is banded lower triangular, and P and Q are permutation
       matrices.
       The matrix Q represents reordering of columns
       for parallelism's sake, while P represents
       reordering of rows for numerical stability using
       classic partial pivoting.