Triang_trunc.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.
 *  _________________________________________________________________________
 */

//
// Triang_trunc.h - generates a triangular truncated distribution
//
// Triang_trunc.h adapted by B. D. Schimel from Uniform.h
// Uniform.h adapted from GNU code by Dirk Grunwald.
//

#ifndef _Triang_trunc_h
#define _Triang_trunc_h

#include "Triangular.h"



class Triang_trunc: public Triangular {

    double sig(double deltab, double dist);

public:

    Triang_trunc(RNG *gen=(RNG*)NULL, double low=0.0, double high=1.0);
    void set_base(double deltab, double lwr, double upr, double x);
};

inline Triang_trunc::Triang_trunc(RNG *gen, double low, double high)
:Triangular(gen,low,high)
{
}

inline void Triang_trunc::set_base(double deltab, double lwr, double upr, 
                                                                double x)
{
  double dist,temp;

  //cutoff factors
  dist = x-lwr;
  sigma_lwr = sig(deltab,dist);
  dist = upr-x;
  sigma_upr = sig(deltab,dist);

  //probability of stepping toward the lower bound
  temp=sigma_lwr-0.5*sigma_lwr*sigma_lwr;
  prob_lwr=temp/(temp+sigma_upr-0.5*sigma_upr*sigma_upr);

}

inline double Triang_trunc::sig(double deltab, double dist)
{
  double sigma;

  //cutoff factor sigma
  if(dist < 0.0)
    sigma=0.0;
  else if(dist < deltab )
    sigma=dist/deltab;
  else
    sigma=1.0;


  return(sigma);

}

#endif