terminal.java

Genetic Programming。GP算法在方程逼近求解上的应用。

/**
*	This is the base class for all kinds of terminal nodes.
*/
public abstract class Terminal extends TreeNode {

        int countNodes() {
                return 1;
        }

        int countNodes(Condition cond) {
                return (cond.test(this)) ? 1 : 0;
        }
        
        

}


class Constant_Value extends Terminal {
        static final double MIN = -4.0;
        static final double MAX = +4.0;
        double value;

        Constant_Value() {
                value = GP.random.nextDouble() * (MAX - MIN) + MIN;
        }

        private Constant_Value(double value) {
                this.value = value;
        }

        public String toString(int level) {
                return indent(level) + value;
        }

        protected Object clone() {
                return new Constant_Value(this.value); };

        String getName() {
                return "Random Constant";
        }

        double eval(double x) {
                return value;
        }

}



class Variable extends Terminal {

        public String toString(int level) {
                return indent(level) + "x";
        }

        protected Object clone() {
                return new Variable();
        }

        String getName() {
                return "x";
        }

        double eval(double x) {
                return x;
        }

}