TriangularGen.java

/*
 * Class:        TriangularGen
 * Description:  random variate generators for the triangular distribution
 * Environment:  Java
 * Software:     SSJ 
 * Copyright (C) 2001  Pierre L'Ecuyer and Universite de Montreal
 * Organization: DIRO, Universite de Montreal
 * @author       
 * @since
 *
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */
package umontreal.ssj.randvar;
 
import umontreal.ssj.rng.*;
import umontreal.ssj.probdist.*;

public class TriangularGen extends RandomVariateGen {
   private double a;
   private double b;
   private double m;

   public TriangularGen(RandomStream s, double a, double b, double m) {
      super(s, new TriangularDist(a, b, m));
      setParams(a, b, m);
   }

   public TriangularGen(RandomStream s, double m) {
      this(s, 0.0, 1.0, m);
   }

   public TriangularGen(RandomStream s, TriangularDist dist) {
      super(s, dist);
      if (dist != null)
         setParams(dist.getA(), dist.getB(), dist.getM());
   }

   public static double nextDouble(RandomStream s, double a, double b, double m) {
      // the code is taken and adapted from unuran
      // file /distributions/c_triangular_gen.c
      return TriangularDist.inverseF(a, b, m, s.nextDouble());
   }

   public double getA() {
      return a;
   }

   public double getB() {
      return b;
   }

   public double getM() {
      return m;
   }

   private void setParams(double a, double b, double m) {
      if ((a == 0.0 && b == 1.0) && (m < 0 || m > 1))
         throw new IllegalArgumentException("m is not in [0,1]");
      else if (a >= b)
         throw new IllegalArgumentException("a >= b");
      else if (m < a || m > b)
         throw new IllegalArgumentException("m is not in [a,b]");
      this.a = a;
      this.b = b;
      this.m = m;
   }
}