Blackman window is a taper formed by using the first three terms of a summation of cosines. It was designed to have close to the minimal leakage possible. ``blackman m`` returns a blackman window.

Hamming window is a taper formed by using a raised cosine with non-zero endpoints, optimized to minimize the nearest side lobe. ``hamming m`` returns a hamming window.

Hann window is a taper formed by using a raised cosine or sine-squared with ends that touch zero. ``hann m`` returns a hann window.

freqz computes the frequency response of a digital filter.

``freqz b a`` computes the frequency response of digital filter with numerator filter coeffecient given by ``b`` (float array) while the denominator filter coeffecient given by ``a`` (float array), and returns the frequencies and the frequency response respectively in real and complex ndarrays. Two optional parameters may be specified: ``n`` is an integer that determines the number of frequencies where the frequency response is to be evaluated, and ``whole`` is a boolean that decides whether the frequency response is two-sided or one-sided. Default values of ``n`` and ``whole`` are 512 and false.