#include <boost/thread.hpp>
#include <iostream>
#include <cstdlib>
#include <ctime>

using namespace std;
int rows;
int cols;
int nthreads;
double **a;
boost::mutex rand_mtx;

void worker(int tid) {
	for (int i = tid;i<rows;i+=nthreads) {
		for (int j = 0;j<cols;j++) {
			double value;
			rand_mtx.lock();
			value = (double) rand()/(RAND_MAX*1.0);
			rand_mtx.unlock();
			a[i][j] = value;
		}
	}
}

int main() {
	srand(time(0));
	rows = 8;
	cols = 6;
	nthreads = 1+rand()%6;
	a=new double*[rows];
	for (int i = 0;i<rows;i++) {
		a[i] = new double[cols];
	}
	boost::thread_group tg;
	for (int t = 0; t<nthreads;t++) {
		tg.create_thread(boost::bind(worker,t));
	}
	tg.join_all();
	for (int i = 0;i<rows;i++) {
		for (int j = 0;j<cols;j++) {
			cout << a[i][j]<<"  ";
		}
		cout<<endl;
	}
	return 0;
}