C - multithreading - calculating sinus of given args

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <math.h>

struct pairs
{
    double val;
    double res;
};

void * calcThread(void * val)
{
        struct pairs * pair = (struct pairs *)val;
        pair->res = sin(pair->val*M_PI/180);
        pthread_exit(0);
}

int main(int argc, char * argv[])
{
        int i = 1;
        struct pairs * values = (struct pairs *)malloc((argc-1) * sizeof(struct pairs));
        pthread_t * threads = (pthread_t *)malloc((argc-1) * sizeof(pthread_t));
        void * tmp;
        for(i; i < argc; i++)
        {
                values[i-1].val = strtod(argv[i], NULL);
                pthread_create(&(threads[i-1]), NULL, &calcThread, (void *)&(values[i-1]));
        }
        for(i = 0; i < argc - 1; i++)
        {
                pthread_join(threads[i], tmp);
                printf("THREAD %lu: sin(%lf) = %lf\n", pthread_self(), values[i].val, values[i].res);
        }
}