gistfile1.txt

TIMES:

stackSqrt  : 185896687
martinSqrt : 174632641
arraySqrt  : 200466799
mathSqrt   : 175357741
listSqrt   : 215584435

NUMBERS: (68)

stackSqrt  : 8.25
martinSqrt : 8.01806640625
arraySqrt  : 8.246211
listSqrt   : 8.246211
mathSqrt   : 8.246211251235321

Sqrt.java

import java.util.ArrayList;
import java.util.Random;


public class Sqrt {
    public static float[] sqrtArray;
    public final static ArrayList<Float> sqrtList = new ArrayList<Float>();
    
    public static void main(String[] args) {
        int max = 100;
        sqrtArray = new float[max];
        for(int i = 0; i < max; i++) {
            float sqrt = (float) Math.sqrt(i);
            sqrtArray[i] = sqrt;
            sqrtList.add(sqrt);
        }
        Random random = new Random();
        int reps = 10000000;
        long time = 0L;
        int number = random.nextInt(max);
        
        System.out.println("\nTIMES:\n");
        
        time = System.nanoTime();
        for(int i = 0; i < reps; i++) {
            stackSqrt(random.nextInt(max));
            //stackSqrt(number);
        }
        time = System.nanoTime() - time; 
        System.out.println("stackSqrt  : " + time);

        time = System.nanoTime();
        for(int i = 0; i < reps; i++) {
            martinSqrt(random.nextInt(max));
            //martinSqrt(number);
        }
        time = System.nanoTime() - time; 
        System.out.println("martinSqrt : " + time);
        
        time = System.nanoTime();
        for(int i = 0; i < reps; i++) {
            arraySqrt(random.nextInt(max));
            //arraySqrt(number);
        }
        time = System.nanoTime() - time; 
        System.out.println("arraySqrt  : " + time);
        
        time = System.nanoTime();
        for(int i = 0; i < reps; i++) {
            mathSqrt(random.nextInt(max));
            //mathSqrt(number);
        }
        time = System.nanoTime() - time; 
        System.out.println("mathSqrt   : " + time);
        
        time = System.nanoTime();
        for(int i = 0; i < reps; i++) {
            listSqrt(random.nextInt(max));
            //listSqrt(number);
        }
        time = System.nanoTime() - time; 
        System.out.println("listSqrt   : " + time);
        
        System.out.println("\nNUMBERS: (" + number + ")\n");
        System.out.println("stackSqrt  : " + stackSqrt(number));
        System.out.println("martinSqrt : " + martinSqrt(number));
        System.out.println("arraySqrt  : " + arraySqrt(number));
        System.out.println("listSqrt   : " + listSqrt(number));
        System.out.println("mathSqrt   : " + mathSqrt(number));

    }
    
    public static double stackSqrt(final double number) {
        double approx = Double.longBitsToDouble(((Double.doubleToLongBits(number) - (1l << 52) ) >> 1) + (1l << 61)); 
        return approx;
    }
    
    public static double martinSqrt(final double number) {
        double approx = Double.longBitsToDouble(((Double.doubleToLongBits(number) >> 32) + 1072632448) << 31);
        //approx = (approx + number / approx) / 2D;
        return approx;
    }
    
    public static float arraySqrt(final int number) {
        return sqrtArray[number];
    }
    
    public static float listSqrt(final int number) {
        return sqrtList.get(number);
    }
    
    public static double mathSqrt(final double number) {
        return Math.sqrt(number);
    }
}