posted 06-09-99 09:19 PM ET            

YEEEK!

posted 06-12-99 02:54 PM ET            

This isn't exactly about Pi, but you sort of look like the crowd that would want to hear this. I wrote a program to find primes, and put it in my startup menu. To date, it has processed 811,543 numbers, of which 64,800 of them are primes. This data is stored in an approximately 1MB file that I doubt you want me to post here, although it'd be a pretty cool way to kill threads . Here's the C source (I don't know if it'll preserve the tab stops):

#include
#include
#include
#include

#define TRUE 1
#define FALSE 0

FILE *primedat, *counter;

unsigned long int prime(unsigned long int in_num)
{
unsigned long int index, in_num2;

in_num2 = in_num / 2;
for (index = 3; index < in_num2; index+=2)
if (in_num % index == 0) return(FALSE);
return(TRUE);
}

void main(void)
{
unsigned long int loopy, old_stop = 3, tot_primes = 0, num_primes = 0;
int num_loop = 1000, total;

// Open primes.txt for appending to
primedat = fopen ("primes.txt", "a");

// Open pcounter.dat for reading
counter = fopen ("pcounter.dat", "r");

// Get last stopping point
fscanf (counter, "%li \n%li ", &old_stop, &tot_primes);

if (primedat==NULL)
{
fclose (primedat);
primedat = fopen ("primes.txt", "w");
fprintf (primedat, "\n2 is prime.\n");
fclose (primedat);
primedat = fopen ("primes.txt", "a");
}

// The main loop
for (loopy = old_stop; loopy < old_stop + num_loop; loopy+=2)
{
if (prime(loopy))
{
fprintf (primedat, "%li is prime.\n", loopy);
num_primes++;
}
}

tot_primes += num_primes;
printf ("\n\nPRIMES.EXE -- STATUS\n");
printf ("--------------------\n\n");
printf ("Last stopping point was %li\n", old_stop);
printf ("The new stopping point is %li\n", loopy); // Status!
printf ("Found %li new primes.\n\n\n", num_primes);
printf ("--------------------\n\n");
printf ("Total number of primes found: %li\n", tot_primes);

fclose(counter);
counter = fopen ("pcounter.dat", "w"); // Reopen counter for writing

// Record where the program left off
fprintf (counter, "%li \n%li ", loopy, tot_primes);
fcloseall();

}