package aima.math;

/**
  * Math functions.
  *
  * Simple math functions to augment those in java.lang.Math.
  *
  * @author Daishi Harada (daishi@cs.berkelely.edu)
  */
public class Function
{
  /**
    * Computes the max of an array of doubles.
    *
    * @param x An array of doubles. x = {x_1, x_2, ... x_n}.
    * @return max_i(x)
    */
  public static double max(double[] x) {
    int n = x.length;
    int i;
    double max;
    if (n == 0) {
      max = Double.NaN;
    } else {
      max = x[0];
      for (i=1;i<n;i++) {
	max = Math.max(max,x[i]);
      }
    }
    return (max);
  }

  /**
    * Computes the index of the max element in an array of doubles.
    *
    * @param x An array of doubles. x = {x_1, x_2, ... x_n}.
    * @return argmax_i(x)
    */
  public static int argmax(double[] x) {
    int n = x.length;
    int i;
    double max;
    int argmax;
    if (n == 0) {
      argmax = -1;
    } else {
      max = x[0];
      argmax = 0;
      for (i=1;i<n;i++) {
	if (max < x[i]) {
	  max = x[i];
	  argmax = i;
	}
      }
    }
    return (argmax);
  }
}