public class Benchmarks {

    public static int product(long[] v1, long[] v2) {
        int sum=1;
        for(int j = 0; j<v1.length;++j)
          sum += v1[j] * v2[j];
        return sum;
    }
    public static int fewerMultiplications(long[] v1, long[] v2) {
        int sum=1;
        for(int j = 0; j<v1.length;j+=2)
          sum += (v1[j] + v2[j]) * ( v1[j+1] + v2[j+1] );
        return sum;
    }
    public static void main(String[] args) {
        int N= 1024*32;
        long[] v1 = new long[N];
        long[] v2 = new long[N];
        long before,after;
        for(int k = 0;k < 5;++k) { // we repeat to be sure
        before = System.currentTimeMillis();
        for(int loop = 1; loop<100000;++loop) product(v1,v2);
        after = System.currentTimeMillis();
        System.out.println("product "+(after-before));
        //
        before = System.currentTimeMillis();
        for(int loop = 1; loop<100000;++loop) fewerMultiplications(v1,v2);
        after = System.currentTimeMillis();
        System.out.println("fewer mults "+(after-before));
        System.out.println();
        }
    }
}