Pearson6Gen.java

/*
 * Class:        Pearson6Gen
 * Description:  random variate generators for the Pearson type VI 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 Pearson6Gen extends RandomVariateGen {
   protected double alpha1;
   protected double alpha2;
   protected double beta;

   public Pearson6Gen(RandomStream s, double alpha1, double alpha2, double beta) {
      super(s, new Pearson6Dist(alpha1, alpha2, beta));
      setParams(alpha1, alpha2, beta);
   }

   public Pearson6Gen(RandomStream s, double alpha1, double alpha2) {
      this(s, alpha1, alpha2, 1.0);
   }

   public Pearson6Gen(RandomStream s, Pearson6Dist dist) {
      super(s, dist);
      if (dist != null)
         setParams(dist.getAlpha1(), dist.getAlpha2(), dist.getBeta());
   }

   public static double nextDouble(RandomStream s, double alpha1, double alpha2, double beta) {
      return Pearson6Dist.inverseF(alpha1, alpha2, beta, s.nextDouble());
   }

   public double getAlpha1() {
      return alpha1;
   }

   public double getAlpha2() {
      return alpha2;
   }

   public double getBeta() {
      return beta;
   }

   public void setParams(double alpha1, double alpha2, double beta) {
      if (alpha1 <= 0.0)
         throw new IllegalArgumentException("alpha1 <= 0");
      if (alpha2 <= 0.0)
         throw new IllegalArgumentException("alpha2 <= 0");
      if (beta <= 0.0)
         throw new IllegalArgumentException("beta <= 0");
      this.alpha1 = alpha1;
      this.alpha2 = alpha2;
      this.beta = beta;
   }
}