Dear all I try to write coeff notch object any comment is welcome so the idea is this :

//notch: H(s) = (s^2 + 1) / (s^2 + s/Q + 1);

// omega = 2*PI*CutOff_Frequency/Sampling_Frequency;

//sn = sin(omega);

//cs = cos(omega);

//alpha = sn/(2*Q);

//a0 = 1;

//a1 = -2*cs;

//a2 = 1;

//b0 = 1 + alpha;

//b1 = -2*cs;

//b2 = 1 – alpha;

//Q= CutOff_Frequency/BW_Coeff

void _coef_notch_Test(short int *Data_In,

short int *Data_Out,

long nData_Length,

double Sampling_Frequency,

double CutOff_Frequency,

double BW_Coeff)

{

{

// If wrong parameters:

if((NULL == Data_In)||(Data_Out)||(nData_Length < = 0)) return;

if((Sampling_Frequency < 0.0)||(CutOff_Frequency < 0.0)) return;

if(CutOff_Frequency > (Sampling_Frequency/2)) return;

if((BW_Coeff < = 0.0)||(BW_Coeff >= 1.0)) return;

//constantes:

static const double PI = 3.141592654;

static const double Sampling_Frequency = 22050;

//filter coefficients :

double a0 = 1;

double a1 = -2 * cos(2*PI*CutOff_Frequency/Sampling_Frequency);

double a2 = 1;

double b0 = 1 + sin(2*PI*CutOff_Frequency/Sampling_Frequency)/(2*(CutOff_Frequency/BW_Coeff));

double b1 = -2 * cos(2*PI*CutOff_Frequency/Sampling_Frequency);

double b2 = 1 – sin(2*PI*CutOff_Frequency/Sampling_Frequency)/(2*(CutOff_Frequency/BW_Coeff));

I try write an equivalent of maxmsp patcher.