Synopsis

PDX_MSGT mth_LuDecomposeBanded(long option, double matrix[], int n, int semi_bw)

Purpose

LU decomposition of banded matrix.

Description

Factors a nxn , banded matrix into lower unit triangular and upper triangular. No row interchanges are done (no pivoting). Hence, this algorithm can fail, even if the matrix is not singular.

Input

option

Not used.

matrix

The horizontal bands of the nxn matrix. There are 2*semi_bw+1 elements in each band (semi_bw elements on either side of the diagonal).

n

The size of the underlying square matrix.

semi_bw

The semibandwidth; ie. there are at most semi_bw nonzero elements to either side of the diagonal.

Output

matrix

Contains the upper and lower triangular components.

Return

      MTH_NOERR
      MTH_SINGULAREQS
      .fi