Code Snippets

Java Source Code

Welcome to Dream.In.Code
	Become a Java Expert! Join 306,728 Java Programmers for FREE! Get instant access to thousands of Java experts, tutorials, code snippets, and more! There are 2,518 people online right now. Registration is fast and FREE... Join Now! Chat LIVE With a Java Expert

Finding Square Root Using Bisection Method

A method which will find the square root of a number, given the number to find the root of, as well as an adjustable precision

Submitted By: erik.price

Actions:

Rating:

Views: 218

Language: Java

Last Modified: November 6, 2009

Instructions: Using bisection might not be the most efficient way of finding square roots, but when given a perfect square, it will find the answer in only 1 iteration

Snippet

public static double biSqrt(double root, double prec) {
double low = 0;
double high = Math.max(root, 1.0); //fixes a bug that would cause numbers less than 1 to fail
double guess = (low+high)/2.0;
int ctr = 0; //ctr is used to make sure that with some
//numbers which can't be represented exactly don't inifitely repeat
if(root < 0){
return Double.longBitsToDouble(0x7ff8000000000000L);
//this represents NaN (Not-a-Number) because negative
//square roots don't work so well
}
else if(root == 0) {
return 0; //prevents it from returning an incorrect result
}
while((Math.abs((guess*guess) - root) > prec) && (ctr < 1000)) //checks to see if the result is "good enough"
{
if((guess*guess) < root)
low = guess;
else
high = guess;
guess = (low+high) / 2.0;
ctr++;
}
return guess;
//just a note: you can remove the prec variable from the method and replace it with an unchanging hardcoded value for set precision
}