/Users/ljp/code/gamma/trunk/Gamma/TransferFunc.h

#ifndef GAMMA_TRANSFER_FUNC_H_INC
#define GAMMA_TRANSFER_FUNC_H_INC

/*  Gamma - Generic processing library
    See COPYRIGHT file for authors and license information */

#include <math.h>
#include <vector>
#include <complex>

namespace gam{


class TransferFunc {
public:
    typedef std::complex<double> Complex;

    TransferFunc(double gain=1): mGain(gain){}

    TransferFunc& addX(double c, double d){ mX.push_back(DelayUnit(c,d)); return *this; }

    TransferFunc& addY(double c, double d){ mY.push_back(DelayUnit(c,d)); return *this; }
    
    TransferFunc& clear(){ mX.clear(); mY.clear(); return *this; }
    
    TransferFunc& gain(double v){ mGain=v; return *this; }
    
    Complex operator()(double f){
        Complex X(0,0), Y(1,0);
        f *= M_2PI;
        for(uint32_t i=0; i<mX.size(); ++i) X += mX[i].response(f);
        for(uint32_t i=0; i<mY.size(); ++i) Y -= mY[i].response(f);
        return X/Y * mGain; // H(z) = Y(z)/X(z)
    }

protected:

    struct DelayUnit{
        DelayUnit(double c_, double d_): c(c_), d(d_){}

        Complex response(double f){
            double phs = f*d;
            return Complex(c*::cos(phs), c*::sin(phs));
        }

        double c, d;
    };

    std::vector<DelayUnit> mX, mY;
    double mGain;
};

} // gam::

#endif