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## Homework Statement

Hello: I have a say N = 7 vector. Say I know that it's DFT is X = [X[0] X[1] ... X[6]]

I am wondering if there is any way that I can find the sum of:

x[1] - x[2] + x[3] - x[4] + x[5] - x[6]?

Since N = odd, I can't use the trick with N/2 = pi as a frequency. Thanks so much.

My signal x{n] is real, but I really can't see any relation between the entries of X and x.