SubOperator.java

public class SubOperator implements Operator {

	
	public void apply(PS interpreter) {
		
		 double b = (Double)interpreter.pop();
	     double a = (Double)interpreter.pop();
	     
	     interpreter.push(new Double(a-b));
	}

	
	public Identifier getName() {
		return new Identifier("sub");
	}

}