PiecewiseConstantFunction.java

/*
 * Class:        PiecewiseConstantFunction
 * Description:  
 * Environment:  Java
 * Software:     SSJ 
 * Copyright (C) 2001  Pierre L'Ecuyer and Universite de Montreal
 * Organization: DIRO, Universite de Montreal
 * @author       Éric Buist
 * @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.functions;
 
import java.util.Arrays;

public class PiecewiseConstantFunction implements MathFunction {
   private double[] x;
   private double[] y;

   public PiecewiseConstantFunction(double[] x, double[] y) {
      if (x.length != y.length)
         throw new IllegalArgumentException();
      this.x = x.clone();
      this.y = y.clone();
   }

   public double[] getX() {
      return x.clone();
   }

   public double[] getY() {
      return y.clone();
   }
 
   public double evaluate(double x) {
      final int idx = Arrays.binarySearch(this.x, x);
      if (idx >= 0)
         return y[idx];
      final int insertionPoint = -(idx + 1);
      return y[insertionPoint];
   }
}