character
chebyshev ripple	db (<0.0)
qfactor (resonator)	(>0.0)
frequency	Alpha Low Alpha Up or samplerate: Hz Lower corner Hz Midi note (69=A440) Upper corner Hz Midi note (69=A440)
more	matched z-transform (better off, check frequency response) prewarp (better on)
output	Signal bits (including sign): -1 bit saturation save brutal shift, this will remove shifts up to 4 positions by changing the factor, hence reducing accuracy by maximum 4 bits but more efficient calculation
execution


//Low pass butterworth filter order=1 alpha1=0.1 
class  FilterBuLp1
{
	public:
		FilterBuLp1()
		{
			v[0]=v[1]=0.0;
		}
	private:
		float v[2];
	public:
		float step(float x) //class II 
		{
			v[0] = v[1];
			v[1] = (2.452372752527856026e-1 * x)
				 + (0.50952544949442879485 * v[0]);
			return 
				 (v[0] + v[1]);
		}
};