EECE 359 MATLAB Exercise 2 1 Introduction 2 Discrete-time ...

EECE359: Matlab Exercise 2 4
3.2 Running the M-file
Use the “Current Directory” window in your Matlab session to change the directory to the
one in which you saved your “animate.m” file.
Now, typeanimate into your Matlab Command Window. This will execute the code you
created in the file “animate.m”. Assuming you copied the code from Section 3.1 properly,
you should see a display window appear with two plots, and demonstrate graphically the
process of convolution.
3.3 Explanation of the Code
Below you will find an explanation of some new Matlab concepts used in the M-file given
in Section 3.1.
• Line 1: clear all removes all previously created variables, and close all closes
all open plot windows.
• Line 11–40: this is a Matlab for loop, which ends with end. The value of n takes on
all integer values from min(t) to max(t). The Matlab functions min and max return
the minimum and maximum values in a vector, respectively.
• Line 12: pause(3) causes Matlab to stop and wait for 3 seconds.
• Line 15: fliplr reverses the contents of a vector → v old= [v1, v2, . . .,vn] to be → v new=
[vn, vn−1, . . .,v1]
• Lines 17–23: this is a Matlab if,then,else structure.
• Lines 19,22: we create a new (temporary) vector by adding zeros at the left or the
right (as required)
• Line 25: this is the actual convolution sum. Note that we are doing the convolution
one step at a time, so we can’t use the Matlab conv function.
• Lines 28, 37: subplot creates two plots inside one plotting window (see the Matlab
help for more details)
• Lines 30,32: hold allows you to “plot-over” an already-existing plot (this is how we
create the overlay of two different functions in the upper plot)
• Lines 33,34,35,39: xlabel, legend, title are various Matlab commands to add text
to your plot. See the help for more details.