Exponential.h

/*  _________________________________________________________________________
 *
 *  UTILIB: A utility library for developing portable C++ codes.
 *  Copyright (c) 2001, Sandia National Laboratories.
 *  This software is distributed under the GNU Lesser General Public License.
 *  For more information, see the README file in the top UTILIB directory.
 *  _________________________________________________________________________
 */

//
// Exponential.h
//
#ifndef __Exponential_h
#define __Exponential_h

#ifndef ANSI_HDRS
#include <math.h>
#else
#include <cmath>
#endif
#include "Uniform.h"



#ifdef SWIG
class Exponential: public CRandVar {
#else
class UTILIB_API Exponential: public CRandVar {
#endif
public:

    Exponential(RNG* gen=0, double _meanval=1.0)
                : CRandVar(gen),uvar(gen) {b=_meanval;}

    double meanval()
                {return b;}
    void meanval(double _b)
                {b=_b;}

#ifndef SWIG

    virtual double operator()();
#endif

protected:

    double b;
    Uniform uvar;
};

#ifndef SWIG


inline double Exponential::operator()()
{
double temp;
RNG* rng;

if ((rng = generator()) == NULL) {
   ErrReturn("Exponential::operator() : Attempting to use a NULL RNG.");
   }
else {
   temp = - b * log( uvar() );
   return(temp);
   }
}
#endif

#endif