//------------
// Introduction to Programming Using Java: An Object-Oriented Approach
//	Arnow/Weiss
//------------
// the squareRoot method
// Chapter 9, Section 9.7, Page 350-353
// MODIFICATIONS:
//    squareRoot and closeEnough are made static here so we
//	can test them without creating an object

import java.io.*; 

class Test_squareRoot {
	///////////////////////////////////////////////////////
	private static boolean closeEnough(double x, double y, double precision) {
		return Math.abs(y*y-x) <= precision;
	}

	// squareRoot returns square root of x within the given precision.
	private static double squareRoot(double x, double precision) {
		double y;
		y = x;
		while (!closeEnough(x, y, precision))
			y = (y+x/y) / 2.0;
		return y;
	}
	///////////////////////////////////////////////////////

	private static boolean squareRootFailure(double x, double p, double v) {
		double w = squareRoot(x,p);
		if ( Math.abs(w*w - v*v) >p) {
			System.err.println("FAILS: squareRoot("  +  x  +  ","  +  p  +
				 ") returns "  +  w  +  " instead of "  +  v);
			return true;
		} else
			return false;
	}

	public static void main(String[] a) {
		double precision=0.00001;
		boolean failure=false;
		failure |= squareRootFailure(4.0,precision,2.0);
		failure |= squareRootFailure(144.0,precision,12.0);
		failure |= squareRootFailure(1000000.0,precision,1000.0);
		if (!failure)
			System.out.println("squareRoot passes our tests");
	}
}