#include <cstdio>
#include <cstdlib>
#include <cmath>
 
#include <sys/time.h>
#include <sys/resource.h>
#include <unistd.h>
 
double get_time()
{
    struct timeval t;
    struct timezone tzp;
    gettimeofday(&t, &tzp);
    return t.tv_sec + t.tv_usec*1e-6;
}
 
int main() {
    double worst_time = 0.0;
    double best_time = 1e6;
 
    volatile double x0 = -M_PI/2.0;
    volatile double foo = atan(x0); // SLOW CALL HERE
    volatile double sum = 0.0; // volatile to avoid having tan() call optimized away
    for (double x = x0; x < M_PI/3.0; x += 0.1) {
        volatile double y = x;
        const double start = get_time();
        const double value = atan(y);
        const double end = get_time();
        sum += value;
 
        const double delta = end - start;
        if (delta > worst_time) {
            worst_time = delta;
        }
        if (delta < best_time) {
            best_time = delta;
        }
        printf("* %f (value: %f)\n", delta, y);
    }
 
    printf("%f / %f\n", worst_time, best_time);
 
    printf("%f\n", foo);
}
 

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