matlab cheby1
I am just copying from MATLAB help file so that it'll help you.
cheby1 designs lowpass, bandpass, highpass, and bandstop digital and analog Chebyshev Type I filters. Chebyshev Type I filters are equiripple in the passband and monotonic in the stopband. Type I filters roll off faster than type II filters, but at the expense of greater deviation from unity in the passband.
[b,a] = cheby1(n,Rp,Wn)
n order
Wn passband edge frequency
Rp dB of peak-to-peak ripple in the passband
If Wn is a two-element vector, Wn = [w1 w2], cheby1 returns an order 2*n bandpass filter with passband w1 <w < w2.
[b,a] = cheby1(n,Rp,Wn,'ftype') designs a highpass , lowpass, or bandstop filter, where the string 'ftype' is one of the following 'high' for a highpass digital filter with normalized passband edge frequency Wn 'low' for a lowpass digital filter with normalized passband edge frequency Wn 'stop' for an order 2*n bandstop digital filter if Wn is a two-element vector, Wn = [w1 w2]. The stopband is w1 < w < w2.
Apart from this you should see the help files of MATLAB.
Bye
Added after 5 minutes:
You can download this attachment for C code and see the implementation