GSLMultiMinFunctionAdapter.h

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// @(#)root/mathmore:$Id: GSLMultiMinFunctionAdapter.h 20882 2007-11-19 11:31:26Z rdm $
// Authors: L. Moneta, 12/2006 

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  * Copyright (c) 2004 ROOT Foundation,  CERN/PH-SFT                   *
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// Header file for class GSLMultiMinFunctionAdapter
//
// Generic adapter for gsl_multimin_function signature 
// usable for any c++ class which defines operator( ) 
// 
// Created by: Lorenzo Moneta  at Fri Nov 12 16:58:51 2004
// 
// Last update: Fri Nov 12 16:58:51 2004
// 
#ifndef ROOT_Math_GSLMultiMinFunctionAdapter
#define ROOT_Math_GSLMultiMinFunctionAdapter

#include "gsl/gsl_vector.h"

namespace ROOT {
namespace Math {




  /**
     Class for adapting any multi-dimension C++ functor class to C function pointers used by 
     GSL MultiMin algorithms. 
     The templated C++ function class must implement: 

    <em> double operator( const double *  x)</em>
    and if the derivatives are required: 
    <em> void Gradient( const double *   x, double * g)</em>
    
    This class defines static methods with will be used to fill the 
    \a gsl_multimin_function and 
    \a gsl_multimin_function_fdf structs used by GSL. 
    See for examples the 
    <A HREF="http://www.gnu.org/software/gsl/manual/html_node/Providing-a-function-to-minimize.html#Providing-a-function-to-minimize">GSL online manual</A>

   @ingroup MultiMin

  */ 
     

  template<class UserFunc> 
  struct  GSLMultiMinFunctionAdapter {
    
    static double F( const gsl_vector * x, void * p) { 
      
      UserFunc * function = reinterpret_cast< UserFunc *> (p);
      // get pointer to data from gsl_vector
      return (*function)( x->data ); 
    }

    
    static void Df(  const gsl_vector * x, void * p,  gsl_vector * g) { 
      
      UserFunc * function = reinterpret_cast< UserFunc *> (p); 
      (*function).Gradient( x->data, g->data );
      
    }

    static void Fdf( const gsl_vector * x, void * p, double *f, gsl_vector * g ) { 
      
      UserFunc * function = reinterpret_cast< UserFunc *> (p);      
//       *f  = (*function) ( x ); 
//       *df = (*function).Gradient( x ); 

      (*function).FdF( x->data, *f, g->data); 
    }

  };


} // namespace Math
} // namespace ROOT


#endif /* ROOT_Math_GSLMultiMinFunctionAdapter */

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