Matlab program for Trapezoidal waveform

Program Code

clc;
clear all;
close all;
t=0:.5:4;
y=trapmf(t,[.5 1 2 2.5]);
plot (t,y);
axis ([0 4 -2 2]);
xlabel ('Time');
ylabel ('Amplitude');
title ('Trapezoidal Waveform');
grid on;                                         

Output 

Explanation of Program Code

 clc;

It clears all input and output from the Command Window display giving clean screen. It removes items from workspace, freeing up system memory. After using clc, the scroll bar cannot be used to see the history of functions, but still the up arrow can be used to recall statements from the command history.

clear all;

It removes all variables from the workspace. This frees up system memory.

close all;

It deletes all figures whose handles are not hidden.

t=0:.5:4;

It results in      

t =[0        .5     1      1.5           2      2.5      3         3.5          4]

Here a vector t is created having starting element as 0.5 and last element as 4 and with an increment of 0.5 between the elements. Here this vector t is used as time axis(x axis) while plotting trapezoidal waveform.

y=trapmf(t,[0.5 1 2 2.5]);

It is used to create trapezoidal curve. Trapmf is trapezoidal-shaped built-in membership function of fuzzy logic toolbox.The trapezoidal curve is a function of a vector, t , and depends on 0.5, 1, 2 and  2.5as given by

f(t,0.5, 1, 2, 2.5)=

 max{min{(t-0.5)/(1-0.5),  1, (2.5-t)/(2.5-2)}  0}

=max{min{(t-0.5)/0.5,   1,   (2.5-t)/0.5}           0}

0.5 and 2.5 locate the "feet" of the trapezoid.

1 and 2 locate the "shoulders" of the trapezoid.

          

plot (t,y);

It plots all the lines defined by t versus y pairs.

axis ([0 4 -2 2]);

It sets the limits for the x- and y-axis of the current axes.

Here according to the above command x-axis begins at 0 and ends at 4. Here y-axis begins at -2 and ends at 2.

xlabel ('Time');

It labels the x-axis as 'Time'. Each axes graphics object can have one label for the x-, y-, and z-axis. The label appears beneath its respective axis in a two-dimensional plot

ylabel ('Amplitude');

It labels the y-axis as ' Amplitude. '

title ('Trapezoidal Waveform');

It outputs the phrase  'Trapezoidal Waveform' above the figure at the top.

grid on; 

It adds major grid lines to the current axes.

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