UnuranDistr.h

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// @(#)root/unuran:$Id$
// Author: L. Moneta Wed Sep 27 11:22:07 2006
 
/**********************************************************************
 *                                                                    *
 * Copyright (c) 2006  LCG ROOT Math Team, CERN/PH-SFT                *
 *                                                                    *
 *                                                                    *
 **********************************************************************/
 
// Header file for class UnuranDistr
 
#ifndef ROOT_Math_UnuranDistr
#define ROOT_Math_UnuranDistr
 
#include "unuran.h"
#include <iostream>
 
#include <cmath>
 
/**
   UnuranDistr
   Provides free function based on TF1 to be called by unuran
*/
 
 
template<class Function>
struct UnuranDistr {
 
   /// evaluate the probal
   static double Pdf(double x, const UNUR_DISTR * dist) {
      const Function * func = reinterpret_cast<const Function *> (  unur_distr_get_extobj(dist) );
      return func->operator()(x);
   }
 
   static double Dpdf(double x,  const UNUR_DISTR * dist) {
      const Function * func = reinterpret_cast<const Function *> (  unur_distr_get_extobj(dist) );
      return func->Derivative(x);
   }
 
   static double Cdf(double x,  const UNUR_DISTR * dist) {
      const Function * func = reinterpret_cast<const Function *> (  unur_distr_get_extobj(dist) );
      return func->Cdf(x);
   }
 
};
 
/**
   free functions for multidimensional functions
   needed bby UNURAN
*/
template<class Function>
struct UnuranDistrMulti {
 
   /// evaluate the probality density function
   static double Pdf(const double * x, UNUR_DISTR * dist) {
      const Function * func = reinterpret_cast<const Function *> (  unur_distr_get_extobj(dist) );
      assert( func != 0);
      return func->operator()(x);
   }
 
 
   static int Dpdf(double * grad, const double * x,  UNUR_DISTR * dist) {
      const Function * func = reinterpret_cast<const Function *> (  unur_distr_get_extobj(dist) );
      func->Gradient(x,grad);
      return 0;
   }
 
   // provides the gradient componets separatly
   static double Pdpdf(const double * x, int coord, UNUR_DISTR * dist) {
      const Function * func = reinterpret_cast<const Function *> (  unur_distr_get_extobj(dist) );
      return func->Gradient(x,coord);
   }
 
   static double Logpdf(const double * x, UNUR_DISTR * dist) {
//       const Function * func = reinterpret_cast<const Function *> (  unur_distr_get_extobj(dist) );
//       assert( func != 0);
//       double y  =  func->operator()(x);
// //       if ( y < std::numeric_limits<double>::min() )
      return  std::log( Pdf(x,dist) );
   }
 
   static int Dlogpdf(double * grad, const double * x,  UNUR_DISTR * dist) {
      int dim = unur_distr_get_dim(dist);
      double pdf = Pdf(x,dist);
      int ret = Dpdf(grad,x,dist);
      for (int i = 0; i < dim; ++i) {
         grad[i] /= pdf;
      }
      return ret;
   }
 
   static double Pdlogpdf(const double * x, int coord, UNUR_DISTR * dist) {
      return  Pdpdf(x,coord,dist)/ Pdf(x,dist);
   }
 
};
 
 
 
#endif /* ROOT_Math_UnuranDistr */