Java --> timing factorials

[danbaron]

I forgot about Java.

But, it's still here.

Here are some factorial timings.

It was run using Java 1.6, from within NetBeans 7.0.

(I agree, the times are strange.)

' code -------------------------------------------------------------------------------------------------

package fact;

import java.math.BigInteger;

public class Fact {

    public static BigInteger factorial(int n) {
        BigInteger product;
        int i;
        product = BigInteger.valueOf(1);
        for (i = 2; i <= n; i++) {
            product = product.multiply(BigInteger.valueOf(i));
        }
        return product;
    }

    public static void main(String[] args) {
        BigInteger value;
        long start, stop;
        double seconds;
        int i, j;
        System.out.println("n!     seconds");
        for (i = 1; i <= 20; i++) {
            j = i * 10000;
            start = System.currentTimeMillis();
            value = factorial(j);
            stop = System.currentTimeMillis();
            seconds = (stop - start) / 1000.0;
            System.out.printf("%06d %07.3f\n", j, seconds);
        }
    }
}

' output -----------------------------------------------------------------------------------------------

n!     seconds
010000 000.768
020000 003.198
030000 007.302
040000 013.405
050000 021.158
060000 032.471
070000 044.814
080000 059.941
090000 075.980
100000 093.814
110000 116.617
120000 136.939
130000 159.905
140000 186.705
150000 313.046
160000 292.847
170000 282.498
180000 325.723
190000 359.425
200000 397.941