Listing 3

//Statevar.h

#ifndef M_PI
#define M_PI        3.14159265358979323846
#endif
#include <math.h>
struct sv {
        double fc;       //corner frequency
        double damp;     //1 over Q
        double lowpass;  //lowpass output
        double bandpass; //bandpass output
        double highpass; //highpass output
        double notch;    //notch output
        double bp_last;
        double lp_last;
        double gain;     //gain
};