Recent content by nrgyyy

could you please help on how the limits of the left side sums would be in that case (τ=t-s)?

Well its easy to see that it works with examples like N=2 or N=3. For example for N=2 the value of both sides is f(1)+f(-1)+2f(0). Same for N=3. I am thinking that maybe I should do a variables change in the first double sums, to end up to a more common summation formula, but I am kinda stuck...

Homework Statement I need some advice on prooving this formula (f is an arbitrary function): \sum^{N}_{t=1}\sum^{N}_{s=1}f(t-s)=\sum^{N-1}_{τ=-Ν+1}(N-|τ|)f(τ) Thanks in advance