trapezoidal wavetable: D1 rising, D2 steady
uniform random number generator in [0, 1)
delta function
unit step function
wavetable generator (interpolation method)
wavetable generator (rounding method)
wavetable generator (truncation method)
complex arithmetic declarations
bandpass/bandstop Butterworth digital filter design
bandpass Chebyshev type 2 digital filter design -1
