# IFFT, negative frequencies and noncausal impulse

When using the IFFT to compute an approximation to the IDTFT, frequency range is 0 to 2$$\pi$$ versus $$-\pi$$ to $$\pi$$. This produces a different impulse sequence(causal I think).

How do you calculate the correct DTFT? Why is the range 0 to $$2\pi$$ used for numerical calculations?

• "freq range is 0 to 2pi instead of -pi to pi": No, it's not. That's up to you / the implementation to define. – Marcus Müller Apr 19 at 13:02