package umontreal.iro.lecuyer.functions;



/**
 * Represents the identity function f (x) = x.
 * 
 */
public class IdentityMathFunction implements MathFunction

,
      MathFunctionWithFirstDerivative, MathFunctionWithDerivative,
      MathFunctionWithIntegral {
   public double evaluate (double x) {
      return x;
   }
   
   public double derivative (double x) {
      return 1;
   }

   public double derivative (double x, int n) {
      return n > 1 ? 0 : 1;
   }

   public double integral (double a, double b) {
      return (b*b - a*a) / 2;
   }
}