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# fourier series.. watch

1. having trouble turning f(x) into a fourier series...

where f(x) = sign(x)
-pi < x < pi

sign(x) = -1, x<0; 0, x=0; 1, x>0

i have an answer for the function as a fourier series, which is

= (4/pi) . sum(n=1,inf){[sin(2k-1)x]/[2k-1]}

this suggests to me that sign(x) is an odd function, as it can be written in terms of only the sine function.. but im sure its not?

any help on where to start?

but i dont really get where i even start?
2. nvm... i see how its odd,

anyone know if the intergral of sign x between [a,-a] is the same equal to 2x?
3. The integral of any odd function between [-a, a] is always zero.

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