/**
 * A pair of measured exponentiation functions.
 *
 * @author Samuel A. Rebelsky
 * @version 1.0 of September 1998
 */
public class MeasuredExponentiation {

  // +--------+---------------------------------------------------
  // | Fields |
  // +--------+

  /** The number of steps used during computation. */
  protected int steps;

  // +---------+--------------------------------------------------
  // | Methods |
  // +---------+

  /**
   * Reset the count of steps to 0.
   */
  public void resetCounter() {
    steps = 0;
  } // resetCounter()

  /**
   * Determine the number of steps used since the last call to
   * resetCounter().
   */
  public int getSteps() {
    return steps;
  } // getSteps()
  
  /**
   * Iteratively compute x^n, for n >= 0.
   */
  public double itExp(double x, double n) {
    double result = 1.0;
    int i;               // A counter
    for (i = 1; i <= n; ++i) {
      ++steps;
      result = result * x;
    } // for
    return result;
  } // itExp(double,int)

  /**
   * Recursively compute x^n, for n >= 0.
   */
  public double recExp(double x, double n) {
    ++steps;
    // Base case: n is 0, x^n is 1.
    if (n == 0) {
       return 1.0;
    } // base case
    // Recursive case: n is 2k.  Compute x^k.
    else if (n%2 == 0) {
      double tmp = recExp(x, n/2);
      return tmp*tmp;
    } // n is even
    // Recursive case: n is odd.  Compute x*x^(n-1).
    else {
      return x * recExp(x, n-1);
    } //n is odd
  } // recExp(double,int)

} // class MeasuredExponentiation