User`s guide

1 Data Processing
If you do not specify channel names when you create the iddata object,
the toolbox assigns default names. By default, the output channels
are n am ed
'y1','y2',...,'yn', and the input channels are named
'u1','u2',...,'un'.
Adding Channels
You can add data channels to an iddat a object.
For example, consider an
iddata object named data that conta ins an input
signal with four channels. To add a fifth input channel, stored as the vector
Input5, use the following syntax:
data.u(:,5) = Input5;
In this example, data.u(:,5) references all samples as (indicated by :)ofthe
input signal
u and sets the values of the fifth channel. This channel is created
when assigning its va lue to
Input5.
You can also combine input channels and output channels of several
iddata
objects into one iddata object using concatenation. For more information, see
“Concatenating iddata Objects” on page 1-65.
Modifying Channel Data
After you create an i dda ta object, you can modify o r remove specific input
and output channels, if needed. You can accomplish this by subreferencing
the input and output matrices and assigning new values.
For example, suppose the
iddata object data contains three output channels
(named
y1, y2,andy3 ), and four input channels (named u1, u2, u3,andu4).
To replace
data such that it only contains samples in y3, u1,andu4,type
the following at the prompt:
data = data(:,3,[1 4])
The resulting data object contains one output channel and two input channels.
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