public class PowerCalc {
  public static void main(String[] args) {
    double x = 5.0;
    System.out.println(x + " to the power 4 is " + power(x,4));
    System.out.println("7.5 to the power 5 is " + power(7.5,5));
    System.out.println("7.5 to the power 0 is " + power(7.5,0));
    System.out.println("10 to the power -2 is " + power(10,-2));
  }

  // Raise x to the power n
  static double power(double x, int n) {
    if(n > 1)
      return x*power(x, n-1);                                          // Recursive call
    else if(n < 0)
      return 1.0/power(x, -n);                                         // Negative power of x
    else
      return n == 0 ? 1.0 : x;                                         // When n is 0 return 1, otherwise x
  }
}