BakerTransformedStream.java

/*
 * Class:        BakerTransformedStream
 * Description:  container class permits one to apply the baker's 
                 transformation to the output of any RandomStream
 * 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.rng;

public class BakerTransformedStream implements RandomStream {
 
   // The base stream.
   private RandomStream st;

   public BakerTransformedStream(RandomStream stream) {
      st = stream;
   }
 
   public void resetStartStream() {
      st.resetStartStream();
   }
 
   public void resetStartSubstream() {
      st.resetStartSubstream();
   }
 
   public void resetNextSubstream() {
      st.resetNextSubstream();
   }

   public String toString() {
      return "Baker transformation of " + st.toString();
   }

   public double nextDouble() {
      double u = st.nextDouble();
      if (u > 0.5)
         return 2.0 * (1.0 - u);
      else
         return u + u;
   }

   public int nextInt(int i, int j) {
      return i + (int) (nextDouble() * (j - i + 1.0));
   }

   public void nextArrayOfDouble(double[] u, int start, int n) {
      st.nextArrayOfDouble(u, start, n);
      for (int i = start; i < start + n; i++)
         if (u[i] > 0.5)
            u[i] = 2.0 * (1.0 - u[i]);
         else
            u[i] += u[i];
   }

   public void nextArrayOfInt(int i, int j, int[] u, int start, int n) {
      for (int ii = start; ii < start + n; ii++)
         u[ii] = nextInt(i, j);
   }
 
}