For complex numbers z, let

f(z) = 2z if z is not real

f(z) = iz if z is real

Find f(i) + f(1) + f(-1) + f(-i).

f(i) = 2i (since i is not real)

f(1) = 1i (since 1 is real)

Solve the other 2 values and add them up.

*You could also solve this problem by noticing that for every f(x) term, there's also a f(-x).

=^._.^=