Question

The butter() command takes in ________

(a) Stopband attenuation

(b) Order of the filter

(c) Ripple frequency

(d) Nothing

I had been asked this question at a job interview.

This interesting question is from Fourier Analysis and Filtering in chapter Beyond the Basics of MATLAB

Answer 1

Right choice is (b) Order of the filter

The best I can explain: The butter command is used to generate the filter co-efficient of a Butterworth filter. This is done by giving the order of the filter and the cut-off frequency as input to the butter filter. The ripple frequency and the stopband attenuation is given to the buttord() function.