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

bool running = true;

void *do_calc(void *in)
{
  size_t y = (size_t)in;
  while (running)
    y *= 1.1;
  return 0;
}

int main() 
{
  int sz = 4;
  pthread_t t[sz];

  for (size_t i=0; i<sz; i++)
    pthread_create(&t[i], NULL, &do_calc, (void*)i);

  for (int i=0; i<5; i++)
    sleep(1);
  running = false;

  for (int i=0; i<sz; i++)
    pthread_join(t[i], 0);

  return 0;
}