# 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