    #include <stdio.h>
    #include <stdlib.h>
    #include <sys/times.h>

    void do_inst();
    double corr ( double *a, double *b, long n );

    double time()
    {
        struct tms t;
        times(&t);
        return (t.tms_utime+t.tms_stime)/100.0;
    }

    int main ( int argc, char **argv )
    {
        int size, count;
        int i;
        double start, end;
        double instrs;
        double *a, *b, c;

        size = argc > 1 ? atoi(argv[1]) : 100000;
        count = argc > 2 ? atoi(argv[2]) : 10000;

        a = malloc(size*sizeof(double)+16);
        b = malloc(size*sizeof(double)+16);
        a = (double *)( (long) a & 0xffffffffffffffc0);
        b = (double *)( (long) b & 0xffffffffffffffc0);
        for ( i = 0; i < size; i++ ) {
            a[i] = i+random()%1000;
            b[i] = i+random()%1000;
        }
        start = time();
        for ( i = 0; i < count; i++ ) {
            c = corr(a,b,size);
            if ( i == 0 ) printf("c = %10.6f\n",c);
        }
        end = time();
        printf("used %10.4f\n",end-start);
        instrs = count * size;
        return 0;
    }