package umontreal.iro.lecuyer.util;

import java.util.Comparator;


/**
 * An implementation of {@link java.util.Comparator} which compares two
 * double arrays by comparing their i-th element,
 * where i is given in the constructor.
 * Method compare(d1, d2) returns -1, 0, or 1 depending on
 * whether d1[i] is less than, equal to, or greater than
 * d2[i].
 * 
 */
public class DoubleArrayComparator implements Comparator  {
   private int i;



   /**
    * Constructs a comparator, where i is the index
    *  used for the comparisons.
    * 
    * @param i index used for comparison
    * 
    */
   public DoubleArrayComparator (int i)  {
      this.i = i;
   }


   /**
    * Returns -1, 0, or 1 depending on
    * whether  d1[i] is less than, equal
    * to, or greater than d2[i].
    * 
    * @param d1 first array
    * 
    *    @param d2 second array
    * 
    * 
    */
   public int compare (double[] d1, double[] d2)  {
      if (i >= d1.length || i >= d2.length)
         throw new IllegalArgumentException("Comparing in a"+
                    "dimension larger than arary dimension");
      return (d1[i]< d2[i] ? -1 : (d1[i] > d2[i] ? 1 : 0));
   } 

}