Discrete Transfer Fcn (Simulink Reference)

Simulink Reference

Discrete Transfer Fcn

Implement a discrete transfer function

Library

Discrete

Description

The Discrete Transfer Fcn block implements the z-transform transfer function described by the following equations:

where m+1 and n+1 are the number of numerator and denominator coefficients, respectively. num and den contain the coefficients of the numerator and denominator in descending powers of z. num can be a vector or matrix, den must be a vector, and both are specified as parameters on the block dialog box. The order of the denominator must be greater than or equal to the order of the numerator.

Block input is scalar; output width is equal to the number of rows in the numerator.

The Discrete Transfer Fcn block represents the method typically used by control engineers, representing discrete systems as polynomials in z. The Discrete Filter block represents the method typically used by signal processing engineers, who describe digital filters using polynomials in z^-1 (the delay operator). The two methods are identical when the numerator is the same length as the denominator.

The Discrete Transfer Fcn block displays the numerator and denominator within its icon depending on how they are specified. See Transfer Fcn for more information.

Data Type Support

A Discrete Transfer Function block accepts and outputs real signals of type double.

Parameters and Dialog Box

Numerator: The row vector of numerator coefficients. A matrix with multiple rows can be specified to generate multiple output. The default is [1].
Denominator: The row vector of denominator coefficients. The default is [1 0.5].
Sample time: The time interval between samples. The default is 1. See Specifying Sample Time in the online documentation for more information.

Characteristics

Direct Feedthrough
Only if the lengths of the Numerator and Denominator parameters are equal

Sample Time
Discrete

Scalar Expansion
No

States
Length of Denominator parameter -1

Dimensionalized
No

Zero Crossing
No

Direct Feedthrough	Only if the lengths of the Numerator and Denominator parameters are equal
Sample Time	Discrete
Scalar Expansion	No
States	Length of Denominator parameter -1
Dimensionalized	No
Zero Crossing	No

Discrete-Time Integrator Discrete Zero-Pole