If we have q= Σ exp(2*pi*j*k*n/N) , for n=0 to M -1
I want to prove a condition for M such as q=0 . .
I'm a bit confused. I start to solve it by knowing that
Σ exp(2*pi*j*k*n/N) , for n=0 to N-1 , = 1- exp(2pi*j*k)/ 1-exp(2pi*j*k/N)
...
thanks in advance
Nikolas