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

long arr[10000];

void *find_first_half(void* arg) {
	double *sin_sum = malloc(sizeof(double));
	double temp;

	int i;
	for(i = 0; i < 5000; i++) {
		temp += sin(arr[i]);
	}

	sin_sum = &temp;
	return (void *) sin_sum;
}

void *find_second_half(void* arg) {
	double *sin_sum = malloc(sizeof(double));
	double temp;
	int i;
	for(i = 5000; i < 10000; i++) {
		*sin_sum += sin((double)arr[i]);
	}

	sin_sum = &temp;
	return (void *) sin_sum;
}

int main() {
	int i;
	for(i = 0; i < 10000; i++) {
		arr[i] = i;
	}

	pthread_t th[2];

	pthread_create(&th[0], NULL, find_first_half, NULL);
	pthread_create(&th[1], NULL, find_second_half, NULL);

	void *first_half, *second_half;

	pthread_join(th[0], &first_half);
	pthread_join(th[1], &second_half);

	printf("%f\n", *(double*)first_half + *(double *)second_half);
}