Backward Substitution (DSP Blockset)

Solve the equation Ux=b for upper triangular matrix U.

Library

Linear Algebra, in Math Functions

Description

The Backward Substitution block solves the linear system Ux=b by simple backward substitution of variables, where U is an upper triangular square matrix. The output is the vector solution of the equations, x.

The block only uses the elements in the upper triangle of the input matrix; the lower elements are ignored. When Force input to be unit-upper triangular is selected, the block replaces the elements on the diagonal of U with ones. This is useful when matrix U 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-upper triangular: Replaces the elements on the diagonal of U with ones when selected.