How to plot partial sums of fourier series?

Question

Teb Keb 2020-12-2

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/674453-how-to-plot-partial-sums-of-fourier-series

回答： Image Analyst 2020-12-2

I am trying to plot a partial sum n=1,2,3 and 10 using for loop function and then plot all the partial sums in one graph.

Below is the code I wrote but somehow it keep giving me error at n==2.

Also how do i plot them in one graph?

x=-pi:0.01:pi;
sum=0;
for n=1:10
    
    
    sum=sum+(pi+(-2/n*cos(n*pi)*sin(n*t)));
    
    if n==1
        plot(x,sum)
    Elseif n==2
        plot(t,sum)
    Elseif n==3
        plot(t,sum)
    Elseif n==10
        plot(t,sum)
    end
end

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Answer 1

Image Analyst 2020-12-2

0
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https://ww2.mathworks.cn/matlabcentral/answers/674453-how-to-plot-partial-sums-of-fourier-series#answer_563478

在 MATLAB Online 中打开

Not exactly sure what formula you want to plot but I think it would be more like this:

clc;    % Clear the command window.
fprintf('Beginning to run %s.m.\n', mfilename);
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
clear global;
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;
x = -pi : 0.01 : pi;
theSum = zeros(1, length(x));
for n = 1 : 10
	theSum = theSum + (pi + (-2./n*cos(n*pi*x) .* sin(n*x)));
	subplot(10, 1, n);
	plot(x, theSum, 'b.-', 'LineWidth', 2)
	grid on;
	drawnow;
	caption = sprintf('n = %d', n);
	title(caption, 'FontSize', 15);
end
g = gcf;
g.WindowState = 'maximized';
fprintf('Done running %s.m.\n', mfilename);