GreensFunction2DAbs.hpp

#ifndef GREENS_FUNCTION_2D_ABS_HPP
#define GREENS_FUNCTION_2D_ABS_HPP
#include <vector>
#include <string>
#include <iostream>
#include <sstream>
#include <stdexcept>

#include "Defs.hpp"

namespace greens_functions
{
class GreensFunction2DAbs
{
  public:

    GreensFunction2DAbs(const Real D, const Real r0, const Real a);
    virtual ~GreensFunction2DAbs();

    const Real drawTime(const Real rnd) const;
    const Real drawR(const Real rnd, const Real t) const;
    const Real drawTheta(const Real rnd, const Real r, const Real t) const;

    const Real p_survival(const Real t) const;
    const Real p_int_r(const Real r, const Real t) const;
    const Real p_int_theta(const Real r, const Real theta, const Real t) const;
    const Real p_int_2pi(const Real r, const Real t) const;

    const Real getD()  const {return this->D;}
    const Real geta()  const {return this->a;}
    const Real getr0() const {return this->r0;}
    const std::string dump() const;
    const char* getName() const
    {
        return "GreensFunction2DAbs";
    }

  private:

    const Real p_int_theta_first(const Real r,
                                 const Real theta,
                                 const Real t) const;

    const Real p_int_theta_second(const Real r,
                                  const Real theta,
                                  const Real t) const;

  private:

    struct p_survival_params
    {
        const GreensFunction2DAbs* const gf;
        const Real rnd;
    };

    struct p_r_params
    {
        const GreensFunction2DAbs* const gf;
        const Real t;
        const Real target;
        /* when time = t, probability of existence is p_surv(t).         *
         * to seek the r, the random value that satisfy the equation     *
         * must be in [0, p_surv). the value, rnd * p_surv(t) is target. */
    };

    struct p_theta_params
    {
        const GreensFunction2DAbs* const gf;
        const Real t;
        const Real r;
        const Real rnd;
    };

    static const Real p_survival_F(const Real t,
                                   const p_survival_params* params);

    static const Real p_r_F(const Real r,
                            const p_r_params* params);

    static const Real p_theta_F(const Real theta,
                                const p_theta_params* params);

  private:

    static const Real CUTOFF;//1e-10, provisionally.

    Real D;
    Real a;
    Real r0;
};
}//greens_functions
#endif//GREENS_FUNCTION_2D_ABS