Generate an Chebyshev type II filter with Rs dB of stop band attenuation.

[b, a] = cheby2(n, Rs, Wc)
low pass filter with cutoff pi*Wc radians

[b, a] = cheby2(n, Rs, Wc, 'high')
high pass filter with cutoff pi*Wc radians

[b, a] = cheby2(n, Rs, [Wl, Wh])
band pass filter with edges pi*Wl and pi*Wh radians

[b, a] = cheby2(n, Rs, [Wl, Wh], 'stop')
band reject filter with edges pi*Wl and pi*Wh radians

[z, p, g] = cheby2(...)
return filter as zero-pole-gain rather than coefficients of the
numerator and denominator polynomials.

[...] = cheby2(...,'s')
return a Laplace space filter, W can be larger than 1.

[a,b,c,d] = cheby2(...)
return  state-space matrices

References:

Parks & Burrus (1987). Digital Filter Design. New York:
John Wiley & Sons, Inc.