threaded_integral.c

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

struct thr_data{
	double b;
	double e;
	double step;
	double count;
};

double func(double arg)
{
	double res;
	res = 1.0;
	return res;
}

void* thr_routine(void* n)
{
	struct thr_data* cur_data = (struct thr_data*)(n);

	printf("New thread: b=%f, e=%f\n", cur_data->b, cur_data->e);

	double h = 0.0;
	double i;
	for (i = cur_data->b; i < cur_data->e; i+=cur_data->step) {
		h += func(i+cur_data->step/2);
	}
	printf("h = %f\n", h);
	cur_data->count += h*cur_data->step;
	return (void*)(&cur_data->count);
} 


/* argv: [1][2] - [a,b], [3]- step,[4] - num of threads*/
int main(int agrc, char* argv[])
{	//a,b - double!!!
	double a = atof(argv[1]);
	double b = atof(argv[2]);
	double s = atof(argv[3]);
	int n = atoi(argv[4]);

	double len = (b-a)/n;

	pthread_t* my_tr = (pthread_t*)malloc(n*sizeof(pthread_t));
	struct thr_data* thr_arr = (struct thr_data*)malloc(n*sizeof(struct thr_data));
	

	int i;
	for (i = 0; i < n; i++) {
		b = a+len;
		thr_arr[i].b = a;
		thr_arr[i].e = b;
		a = b;
		thr_arr[i].step = s;
		thr_arr[i].count = 0.0;
		printf("Struct %d: beg %f end %f step %f\n", i, thr_arr[i].b, thr_arr[i].e, thr_arr[i].step);
	}
	
	for (i = 0; i<n; i++) {
		int pthread_create_status;
		pthread_create_status = pthread_create(&my_tr[i], NULL, thr_routine, (void*)(&thr_arr[i]));
	}

	double sum = 0.0;
	int pthread_join_status;
	for(i = 0; i < n; i++) {
		void* res;
		pthread_join_status = pthread_join(my_tr[i], &res);
		printf("%f\n", *(double*)(res));
		sum += *(double*)(res);
		
	}
	printf("=====================%f\n", sum);
	return 0;
}