Complete Square Root Program

In the completed program, the roles of oldGuess and of newGuess can both be played by the variable guess. The value for oldGuess is used on the right of the = sign. After a value for newGuess is calculated, it is assigned to the variable guess on the left of the = sign.

class  SquareRoot
{

  public static void main( String[] args ) 
  {
    final double smallValue = 1.0E-14 ;
    double N     = 3.00 ;
    double guess = 1.00 ;

    while ( Math.abs( N/(guess*guess) - 1.0 ) > smallValue )
    {
       // calculate a new value for the guess
       guess =  N/(2*guess) + guess/2 ;

    }

    System.out.println("The square root of " + N + " is " + guess ) ;
  }

}

Here is the output of the program:

C:JavaLessons\chap19>java SquareRoot

The square root of 3.0 is 1.7320508075688772

The last several digits of this output are probably in error since the program only computes 14 decimal places of accuracy.