butter

Signal Processing

Butterworth lowpass filter design. Returns {b, a} filter coefficients for an nth-order filter with normalized cutoff frequency Wn (0 to 1, where 1 is Nyquist). Use with filter() or filtfilt() to apply.

butter(n, Wn)

butter(n, Wn, type)

h = butter(4, 0.3); filter(h.b, h.a, randn(100))

h = butter(6, 0.1); freqz(h.b, h.a)