User`s guide

Forward Substitution

5-213

5Forward Substitution

Purpose Solve the equation LX=B for X when L is a lower triangular matrix.

Library Math Functions / Matrices and Linear Algebra / Linear System Solvers

Description The Forward Substitution block solves the linear system LX=B by simple

forward substitution of variables, where L is the lower triangular M-by-M

matrix input to the

L port, and B is the M-by-N matrix input to the B port. The

output is the solution of the equations, the M-by-N matrix X, and is always

sample-based.

The block only uses the elements in the lower triangle of input L; the upper

elements are ignored. When

Force input to be unit-lower triangular is

selected, the block replaces the elements on the diagonal of L with ones. This

is useful when matrix L is the result of another operation, such as an LDL

decomposition, that uses the diagonal elements to represent the D matrix.

A length-M vector input at port

B is treated as an M-by-1 matrix.

Dialog Box

Force input to be unit-lower triangular

Replaces the elements on the diagonal of L with 1s when selected. Tunable.

Supported

Data Types