Good Random Number Generator

Hi,

Im using the Monte Carlo method to get an estimate of Pi.

I generate numbers between 0.0 and 1.0, using the following function (similar to the one in the FAQ)

Code:

---

double generate_rand(double min, double max)
{

  static int Init = 0;
  double rc;
 
  if (Init == 0)
  {
    srand(time(NULL));
    Init = 1;
  }
  rc =  (rand() / (RAND_MAX + 1.0) * (max - min) + min);
  return rc;
}

---

The estimation of pi depends on the quality of the random number generator, I was wondering if there is any way to make my function generate 'better' random numbers?

>I was wondering if there is any way to make my function generate 'better' random numbers?

http://www.stanford.edu/~blp/writings/clc/random.html ?

You could use a 64bit random number generator. You can build one by using 64-bit numbers and bit-shifting 24-bit random digits from rand().

You could combine rand with XORs. As more, as better.

Code:

---

int cnt;
int res = rand();
for(cnt=rand()&0x07;cnt>=0;cnt--)
    res = res ^ rand();

---

But wouldn't be any good algorithm... just to clean your hand from time to time

Take a look at the Mersenne Twister pseudo-random number generator.