User`s guide

2 LTI Models
2-36
Note that
tf(0.1,[1 –1],0.1) + tf(1,[1 0.5],0.5)
returns an error message.
??? Error using ==> lti/plus
In SYS1+SYS2, both models must have the same sample time.
Caution: Resettingthesampletimeof acontinuous-timeLTImodel sys from
zero to a nonzero value does not discretize the original model
sys.The
command
set(sys,'Ts',0.1)
only affects the Ts property and does not alter the remaining model data. Use
c2d and d2c to perform continuous-to-discrete and discrete-to-continuous
conversions. For example, use
sysd = c2d(sys,0.1)
to discretize a continuous system sys at a 10Hz sampling rate.
Use d2d to change the sample time of a discrete-time system and resample it.
Input Names and Output Names
You can use the InputName and OutputName properties (in short, I/O names) t o
assign names to any or all o f the input and output channels in your LTI model.
For example, you can create a SISO model with input
thrust, output
velocity, and transfer function by typing
h = tf(1,[1 10]);
set(h,'inputname','thrust','outputname','velocity',...
'variable','p')
Equivalently, you can set these properties directly by typing
h = tf(1,[1 10],'inputname','thrust',...
'outputname','velocity',...
'variable','p')
Hp
()
1 p 10
+()⁄=