# Synopsis

PDX_MSGT mth_ForBackSubstitution(long option, double matrix[], int n, int semi_bw, double rhs[], double sol[])

# Purpose

Forward/backward substitution after LU decomposition (banded).

# Description

Does the forward/backward substitution using the lower unit triangular and upper triangular factors produced by mth_LuDecomposeBanded.

# Input

## option

Not used.

## matrix

The horizontal bands of the nxn matrix containing the lower unit triangular and upper triangular factors.

## 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.

## rhs

The right hand side of the system of linear equations. The input values are destroyed in this routine.

# Output

## sol

The solution vector of the system of linear equations.

# Return

MTH_NOERR