int main(int argc, const char *argv[])
{
    double d;
    clock_t begin_time, end_time;

    if(argc!=2)
    {
        fprintf(stderr, "Usage: %s name_of_file\n", argv[0]);
        return -1;
    }

    begin_time = clock();
    printf("f(%s, &d) returned %d\n", argv[1], f(argv[1], &d));
    end_time = clock();
    printf("d==%.16lf\ntime==%lf\n", d, (double)(end_time - begin_time)/CLOCKS_PER_SEC);

    return 0;
}