Run a program on multithreads and compare speed!

I need to run a program on different ammounts of threads so I can compare the times spend.
My initial program is this one, a mount carlo simulation:

Code:

---

#include <stdlib.h>
    #include <stdio.h>
    #include <math.h>
    #include <string.h>
    #include <time.h>
    #define SEED 35791246
   
    main(int argc, char* argv)
    {
      int points=10000000;
      double x,y;
      int i,count=0;
      double z;
      double pi;
   
      clock_t begin = clock();
   
      srand(SEED);
      count=0;
      for ( i=0; i<points; i++) {
          x = (double)rand()/RAND_MAX;
          y = (double)rand()/RAND_MAX;
          z = x*x+y*y;
          if (z<=1) count++;
          }
      pi=(double)count/points*4;
      printf("The number o variables is %d , and the pi estimation is %g \n",points,pi);
   
      clock_t end = clock();
      double time_spent = (double)(end - begin) / CLOCKS_PER_SEC;
      printf("Time Spent: %f  \n", time_spent);
    }

---

Everything works fine, but now I need to run it differents amounts of threads, let's say 2 and 4, I tried this but its not working:

Code:

---

    #include <stdlib.h>
    #include <stdio.h>
    #include <math.h>
    #include <string.h>
    #define SEED 35791246
    #define NUM_THREADS1 2
    #define NUM_THREADS2 4
   
    main(int argc, char* argv)
    {
   
      pthread_t thread1, thread2;
      pthread_t thread1[NUM_THREADS1]
      pthread_t thread2[NUM_THREADS2]
   
   
      int points=10000000;
      double x,y;
      int i,count=0;
      double z;
      double pi;
   
      srand(SEED);
      count=0;
      for ( i=0; i< NUM_THREADS1; i++) {
          x = (double)rand()/RAND_MAX;
          y = (double)rand()/RAND_MAX;
          z = x*x+y*y;
          if (z<=1) count++;
          }
      pi=(double)count/points*4;
      printf("The number o variables is %d , and the pi estimation is %g \n",points,pi);
   
      srand(SEED);
      count=0;
      for ( i=0; i< NUM_THREADS2; i++) {
          x = (double)rand()/RAND_MAX;
          y = (double)rand()/RAND_MAX;
          z = x*x+y*y;
          if (z<=1) count++;
          }
      pi=(double)count/points*4;
      printf("The number o variables is %d , and the pi estimation is %g \n",points,pi);
    }

---

I'm new to threads so I could use a little input on how to solve this. Thank you in advance!

What's with the freaky topic?

A short example of how to pass parameters to a thread, and get results back from a thread.

Code:

---

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

typedef struct {
  int  num_points;
} thread_param_t;

typedef struct {
  int  num_points;
} thread_result_t;

void *worker(void *p) {
  thread_param_t *param = p;
  printf("Thread called with %d\n", param->num_points);
  free(param);

  // malloc here, main is responsible for free
  thread_result_t *result = malloc(sizeof(*result));
  result->num_points = 42;
  return result;
}

int main()
{
  pthread_t tid;

  // malloc here, thread is responsible for free
  thread_param_t  *param = malloc(sizeof(*param));
  param->num_points = 1234;

  pthread_create(&tid,NULL,worker,param);

  void *p;
  pthread_join(tid,&p);

  thread_result_t *result = p;
  printf("Got result from thread=%d\n", result->num_points);
  free(result);

}

---

This was supposed to be the title, sorry - Run a program on multithreads and compare speed!

OK, done.

it that enough

Quote:

---

Originally Posted by Kenny844

it that enough

---

Is what enough?