/***************************************************************************
 * Copyright (C) 1995, 1996, Jun Sun, jsun@junsun.net.                     *
 *                                                                         *
 ***************************************************************************
 */

#include <assert.h>
#include "random_variates.h"

Bernoulli::Bernoulli(double p)
{ 
  assert((p>=0.0) && (p<=1.0));
  
  _p = p; 
}

Bernoulli::Bernoulli(int *data, int num_data)
{ double sum = 0.0;
  int i;

  assert(data);
  assert(num_data>0);
  for(i=0;i<num_data;i++) assert( (data[i]==0) || (data[i]==1));

  for(i=0;i<num_data;i++)
    sum += (double) data[i];

  _p = sum / (double) num_data;
}


Bernoulli::~Bernoulli() {}


double Bernoulli::mass(int x)
{ if (x==0) return 1.0-_p;
  else if (x==1) return _p;
       else 
       { mythrow("x is not 0 nor 1 in Bernoulli::mass");
         return -1.0;
       }
}

double Bernoulli::distribution(double x)
{ if (x<0.0) return 0.0;
  if (x>=1.0) return 1.0;
  return 1-_p;
}


int Bernoulli::sample()
{
  if (randp->sample() <= _p) return 1;
  else return 0;
}