fourier series coefficients.

[truble@mill]

I'm using fourier_an and fourier_bn. Results are unreliable. Result is often 'undef'. See attached.
an_setup_1 shows setup for cosine coefficients.
an_setup_2 shows result. Undef.
an_setup_help_page shows Prime help suggestions.
fourier_bn working example shows typical results expected.

BTW, fourier_an results should be +/- 8/n*pi for n odd and 0 for n even.
Can anyone explain my error? Thank you.

[parisse]

The CAS can only handle integration of piecewise with one linear inequation.
Workaround: rewrite your expression under this constraint. For example
fourier_an(-2+4*piecewise(x>-pi/2,1,0)*piecewise(x<pi/2,1,0),n)

[truble@mill]

Thank you for your reply. It certainly works but I do not follow your workaround.
Could you add some explanation? For example, why you decided x>-pi/2 and what the other parameters are inside the piecewise function.
Thanking you.

[parisse]

Much better workaround:
fourier_an(piecewise(x<-pi/2,-2,x<pi/2,2,-2),n)

[truble@mill]

Yes. Agreed. I'll be able to adapt that code. Thanking you again.