User`s guide

Table Of Contents

Creating LTI Models

2-9

where num and den are row vectors listing the coefficients of the polynomials

and , respectively, when these polynomials are ordered in descending

powers of s. The resulting variable

h is a TF object containing the numerator

and denominator data.

For example, you can create the transfer function by

typing

h = tf([1 0],[1 2 10])

MATLAB responds with

Transfer function:

--------------

s^2 + 2 s + 10

Note the customized display used for TF objects.

You can also specify transfer functions as rational expressions in the L aplace

variable s by:

1 Defining the variable s as a special TF model

s = tf('s');

2 Entering your transfer function as a rational expression in s

For example, once s is defined with tf as in 1,

H = s/(s^2 + 2*s +10);

produces the same transfer function as

h = tf([1 0],[1 2 10]);

Note: You need only define the variable s as a TF model once. All of the

subsequent models you create using rational expressions of

s are specified as

TF objects, unless you convert the variable

s to ZPK. See “Model Conversion”

on page 2-42 for more information.

()

2s10

++()⁄=