exit.h

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#ifndef EXIT_H
#define EXIT_H

#include <itpp/itbase.h>
#include <itpp/comm/modulator.h> //BPSK class for a priori information generation
#include <itpp/itexports.h>

namespace itpp
{

class ITPP_EXPORT EXIT
{
public:

    double apriori_mutual_info(const double &in_sigma2A, 
                               const double &lim=100 
                              )
    {
        _gaussian_fct = Gaussian_Fct(in_sigma2A);
        return 1.0-itpp::quad(_gaussian_fct, -lim, lim);
    };

    itpp::vec generate_apriori_info(const itpp::bvec &bits)
    {
        itpp::BPSK bpsk;
        double sigma2A = _gaussian_fct.sigma();
        return (-sigma2A/2)*bpsk.modulate_bits(bits)+std::sqrt(sigma2A)*itpp::randn(bits.length());
    };

    double extrinsic_mutual_info(const itpp::vec &obs, 
                                 const itpp::bvec &cond, 
                                 const int &N=100 
                                );
private:
    class ITPP_EXPORT Gaussian_Fct
    {
        double _sigma;
      public:
        Gaussian_Fct(): _sigma(0.0){}
        Gaussian_Fct(double sigma): _sigma(sigma){}
        double sigma() const {return _sigma;}
        double operator()(double x) const;
    };
    Gaussian_Fct _gaussian_fct;
};

}
#endif /* EXIT_H_ */