butter Butterworth filter design.. [b, a] = butter (n, wc) [b, a] = butter (n, wc, "high") [b, a] = butter (n, [wl, wh]) [b, a] = butter (n, [wl, wh], "stop") [z, p, g] = butter (…) […] = butter (…, "s") n: positive integer value (order of filter). wc: positive real value, 1).Normalised digital 3dB cutoff frequency/frequencies for digital filter, in the range [0, 1] {dimensionless} 2).Analog 3dB cutoff frequency/frequencies for analog filter, in the range [0, Inf] {rad/sec} This function generates a Butterworth filter. Default is a discrete space (z) or digital filter using Bilinear transformation from s to z plane. If second argument is scalar the third parameter takes in low or high, default value is low. The cutoff is pi*wc radians. [b,a] = butter(n, [wl, wh]) indicates a band pass filter with cutoffs pi*Wl and pi*wh radians. [b,a] = butter(n, [wl, wh], ’stop’) indicates a band reject filter with cutoffs pi*wl and pi*wh radians. [z,p,g] = butter(...) returns filter as zero-pole-gain rather than coefficients of the numerator and denominator polynomials. [...] = butter(...,’s’) returns a Laplace space filter,here cutoff(s) wc can be larger than 1 (rad/sec). Sonu Sharma, RGIT Mumbai (fellow at FOSSEE, IIT Bombay)