4/10/08
example (Fig1)
example (Fig2)
use prewarping to help match original analog transfer function (Fig3)
wi` = 2/T * tan(wiT/2)
same for wp and ws
be sure to look at tables 7.1 and 7.2
bilinear transformations s = 2/T * (z-1)/(z+1)

numerical computation of DTFT on computer
assume we have a CT signal and sample it with period T giving N samples (Fig4)
sampling the repeating spectrum causes the original signal to repeat
fast fourier transform (comparison on Fig5)