# Variable notation for DTFT?

1. ### Jammin_James

49
Can someone explain to me why sometimes I see the DTFT as functions of capital omegas or e^(jomega).

I'm failing to see the reason.

2. ### marcusl

2,149
$$\Omega$$ usually refers to continuous frequency, which is often appropriate for the DTFT. The z transform is also used heavily in DSP, and it covers the full complex plane. Use of $$exp(j\omega)$$ makes it very clear that you are evaluating the frequency response (which is on the unit circle).