Fourier series of a 2step function?





how do you do a fourier series of



Fx =     0   -10<x<-5
           -5      -5<x<0
            5      0<x<5
            0      5<x<10



                   |----------|
                   |          |
                   |          |
--------|          |          |----------
        |          |
        |----------|
  

thanks in advance


Doug