Forward Substitution (DSP Blockset)

Solve the equation Lx=b for lower triangular matrix L.

Library

Linear Algebra, in Math Functions

Description

The Forward Substitution block solves the linear system Lx=b by simple forward substitution of variables, where L is a lower triangular square matrix. The output is the vector solution of the equations, x.

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

The block may generate NaN or Inf for underdetermined or inconsistent systems.

Dialog Box

Force input to be unit-lower triangular: Replaces the elements on the diagonal of L with ones when selected.