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Why does my program not graph my function (line 17)?

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Jesus Marcial
Jesus Marcial on 24 Sep 2018
Edited: OCDER on 24 Sep 2018
t = [-2:.001:2];
y = 0.5*square(2*pi*t,50)+0.5;
plot(t,y);
xlabel('Time');
title('Square wave with 50% duty cycle Marcial');
grid on;
axis([-2 2 -1 2]);
x0=.5;
syms n t;
h1 = x0 + (1-cos(pi)*(sin(2*pi*t))/pi); %1st harmonic
h3 = x0 + symsum((1-cos(pi*n)*(sin(2*pi*t))/pi*n),n,1,3); %third harmonic
h5 = x0 + symsum((1-cos(pi*n)*(sin(2*pi*t))/pi*n),n,1,5); %fifth harmonic
h7 = x0 + symsum((1-cos(pi*n)*(sin(2*pi*t))/pi*n),n,1,7); %seventh harmonic
h20 = x0 + symsum((1-cos(pi*n)*(sin(2*pi*t))/pi*n),n,1,20); %20th harmonic
h100 = x0 + symsum((1-cos(pi*n)*(sin(2*pi*t))/pi*n),n,1,100); %100th harmonic
hold on;
plot(t,h1);
I am trying to approximate a square wave with it's fourier series. The final line is giving me an error: "Data must be numeric, datetime, duration or an array convertible to double." I am not sure what this means. I have attempted to plot both the square wave and the function h1 using the same line (and subsequent plotting data after calculating harmonics), but that does not work either. Thank you for your time.

Accepted Answer

OCDER
OCDER on 24 Sep 2018
Edited: OCDER on 24 Sep 2018
Use fplot to plot symbolic equations, and use plot to plot vectors x and y. See: https://www.mathworks.com/help/symbolic/fplot.html
t = [-2:.001:2];
...
syms n t %you overwritten t as a symbolic variable
plot(t, h1) %can't plot it, as t is not a vector anymore
fplot(h1, [-2, 2]) %This should work, as h1 is a symbolic function that you want to plot t = -2 to 2

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