/**
  * Copyright (c): Uwe Schmidt, FH Wedel
  *
  * You may study, modify and distribute this source code
  * FOR NON-COMMERCIAL PURPOSES ONLY.
  * This copyright message has to remain unchanged.
  *
  * Note that this document is provided 'as is',
  * WITHOUT WARRANTY of any kind either expressed or implied.
  */

/*
   interface for creating predefined
   Function objects for simple
   math functions

   these functions can be used
   simply by "implementing" this interface
   e.g.:

   class X implements MathFunctions {
     ... exp ... sin ...
   }
*/

interface MathFunctions {

  static
  RealFunction exp =
    new RealFunction() {
        public
	double at(double x) {
	  return
	    Math.exp(x);
	}

      public
      String toString() {
	return
	  "exp(x)";
      }
    };

  static
  RealFunction log =
    new RealFunction() {
      public
      double at(double x) {
	return
	  Math.log(x);
      }

      public
      String toString() {
	return
	  "log(x)";
      }
    };

  static
  RealFunction sin =
    new RealFunction() {
      public
      double at(double x) {
	return
	  Math.sin(x);
      }

      public
      String toString() {
	return
	  "sin(x)";
      }
    };

  static
  RealFunction sqr =
    new RealFunction() {
      public
      double at(double x) {
	return
	  x * x;
      }

      public
      String toString() {
	return "x * x";
      }
    };
}