What is the error in this computation?
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Here I want to plot a simple sum.
I computed it manually by iterating different values, and then did it same by using for loop, but there is some mistake, can somebody figure it out for me.
Below given is my code:
x = 0:pi/16:pi;
s = (8/(pi*(1^3)))*sin(1*x)+...
(8/(pi*(3^3)))*sin(3*x)+...
(8/(pi*(5^3)))*sin(5*x)+...
(8/(pi*(7^3)))*sin(7*x)+...
(8/(pi*(9^3)))*sin(9*x)+...
(8/(pi*(11^3)))*sin(11*x)+...
(8/(pi*(13^3)))*sin(13*x)+...
(8/(pi*(15^3)))*sin(15*x);
ss = 0;
for k =1:16
ss = ss + (8/(pi*(k^3)))*sin(k*x);
end
plot(x,s,'b-',x,ss,'r-');
Why I choose odd values in manual sum because sin(k*pi) = 0, where k=2,4,... ,but i took all (even and odd) values in for loop
The plot generated is given below:
![123.bmp](https://www.mathworks.com/matlabcentral/answers/uploaded_files/259720/123.bmp)
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Walter Roberson
2020년 1월 4일
sin(k*pi) is 0 for integer k but you have sin(k*x) where x is a fraction of pi and that does not vanish.
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Steven Lord
2020년 1월 4일
In theory sin(k*pi) is 0 for integer k. In practice if you're computing sin(k*pi) consider using the sinpi function introduced in release R2018b.
sin(pi) % not exactly 0
sinpi(1) % exactly 0
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