/*****************************************************************************

 JEP 2.4.1, Extensions 1.1.1
      April 30 2007
      (c) Copyright 2007, Nathan Funk and Richard Morris
      See LICENSE-*.txt for license information.

 *****************************************************************************/
package weasel.jep.function;


import java.util.Stack;

import weasel.jep.ParseException;
import weasel.jep.type.Complex;


public class SquareRoot extends PostfixMathCommand {
	public SquareRoot() {
		numberOfParameters = 1;
	}

	/**
	 * Applies the function to the parameters on the stack.
	 */
	@Override
	public void run(Stack inStack) throws ParseException {

		checkStack(inStack);// check the stack
		Object param = inStack.pop();
		inStack.push(sqrt(param));//push the result on the inStack
		return;
	}

	/**
	 * Calculates the square root of the parameter. The parameter must either be
	 * of type Double or Complex.
	 * 
	 * @return The square root of the parameter.
	 */
	public Object sqrt(Object param) throws ParseException {
		if (param instanceof Complex) return ((Complex) param).sqrt();
		if (param instanceof Number) {
			double value = ((Number) param).doubleValue();

			// a value less than 0 will produce a complex result
			if (value < 0.0) {
				return (new Complex(value).sqrt());
			} else {
				return new Double(Math.sqrt(value));
			}
		}

		throw new ParseException("sqrt() not defined for " + param.getClass().getSimpleName());
	}
}
