musicdsp.org source code archive - WSInf

chebyshev waveshaper (using their recursive definition) (click this to go back to the index)
Type : chebyshev
References : Posted by mdsp
Notes :
someone asked for it on kvr-audio.
I use it in an unreleased additive synth.
There's no oversampling needed in my case since I feed it with a pure sinusoid and I control the order to not have frequencies above Fs/2. Otherwise
you should oversample by the order you'll use in the function or bandlimit the signal before the waveshaper. unless you really want that aliasing
effect... :)
I hope the code is self-explaining, otherwise there's plenty of sites explaining chebyshev polynoms and their applications.
Code :
float chebyshev(float x, float A[], int order)
{
// To = 1
// T1 = x
// Tn = 2.x.Tn-1 - Tn-2
// out = sum(Ai*Ti(x)) , i C {1,..,order}
float Tn_2 = 1.0f;
float Tn_1 = x;
float Tn;
float out = A[0]*Tn_1;
}
for(int n=2;n