Function for fourier series

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Rayan  Maye
Rayan Maye on 24 Feb 2022
Commented: Star Strider on 24 Feb 2022
hello
I have written a function for fourier series but when i try to plot it ,only the consine one shows up did I forget something ? Danke schön
function ft = signal(S,t,A,M,T,N)
for n=1:N
if S=="square"
ft=M+sum(((4*A)./(n.*pi)).*sin((n.*pi)/2).*cos((2*n.*pi.*t)./T));
elseif S=="triangle"
ft=M+sum(((8*A)./(n.^2*pi^2)).*cos((2*n*pi.*t)./T));
elseif S=="saw"
ft=M+sum(-1^(n+1).*(2*A./n.^pi).*sin((2*n.*pi*t)./T));
elseif S=="cosine"
ft=M+A*cos((2*pi.*t)./T);
end
end
%%plot part
M=0;
A=1;
T=10;
t=0:0.1:60;
N=10;
grid on
ft=signal("square",t,A,M,T,N);
plot(t,ft,'r')
hold on
ft=signal("triangle",t,A,M,T,N);
plot(t,ft,'b')
hold on
ft=signal("saw",t,A,M,T,N);
plot(t,ft,'g')
hold on
ft=signal("cosine",t,A,M,T,N);
plot(t,ft,'k')
%%

Accepted Answer

Star Strider
Star Strider on 24 Feb 2022
Edited: Star Strider on 24 Feb 2022
Try this —
%%plot part
M=0;
A=1;
T=10;
t=0:0.1:60;
N=10;
figure
subplot(4,1,1)
ft=signal("square",t,A,M,T,N);
plot(t,ft,'r')
subplot(4,1,2)
ft=signal("triangle",t,A,M,T,N);
plot(t,ft,'b')
subplot(4,1,3)
ft=signal("saw",t,A,M,T,N);
plot(t,ft,'g')
subplot(4,1,4)
ft=signal("cosine",t,A,M,T,N);
plot(t,ft,'k')
%%
function ft = signal(S,t,A,M,T,N)
n=(1:N).';
if S=="square"
ft=M+sum(((4*A)./(n.*pi)).*sin((n.*pi)/2).*cos((2*n.*pi.*t)./T));
elseif S=="triangle"
ft=M+sum(((8*A)./(n.^2*pi^2)).*cos((2*n*pi.*t)./T));
elseif S=="saw"
ft=M+sum(-1.^(n+1).*(2*A./n.^pi).*sin((2*n.*pi*t)./T));
elseif S=="cosine"
ft=M+A*cos((2*pi.*t)./T);
end
end
The loop was not executing correctly. I eliminated the for loop and changed the code to use ‘n’ as a column vector to take advantage of MATLAB’s vectorisation abilities. (I plotted them as subplots because I wanted to see the individual results more clearly.) Otherwise (except for a minor change in the ‘saw’ calculation) the code is unchanged.
EDIT — (24 Feb 2022 at 15:06)
Changed original answer text to one that actually addresses the problem.
.
  2 Comments
Rayan  Maye
Rayan Maye on 24 Feb 2022
How dumb of me of not vectorizing n,thanks for your help mate
Star Strider
Star Strider on 24 Feb 2022
As always, my pleasure!

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More Answers (1)

Rayan  Maye
Rayan Maye on 24 Feb 2022
Tried it ,did'nt work but thanks.I'm suspecting the problem is maybe a mistake that I did in the transcription of mathematical formulas.

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