Help with Piecewise function

[salvomic]

(02-01-2015 04:10 PM)parisse Wrote:  what's wrong? Your function is odd.

oh, you are right!
f(t)*cos(t) should be odd and the right formula should be, in this case: bk = (1/π)*Int(f(t)*sin(kt),t,-pi,pi) and all ak are 0...
The result (in my book) it's 4/(kπ) if k is odd (like the formula of XCAS: fourier_bn(f(t),t,2*pi,n,-pi) returns (-(-1)^n*2+2)/(n*pi)), I think...

I must rewrite my program for Fourier!

Off topic: there is in Prime a way to check if a function is even or odd? It would be useful for my program

Thank you

salvo