#include "defs.h"
#include "externs.h"


CheckPrime(K)
   int K;

{  int J;

   /* the plan:  see if J divides K, for all values J which are
      
         (a) themselves prime (no need to try J if it is nonprime), and
         (b) less than or equal to sqrt(K) (if K has a divisor larger
             than this square root, it must also have a smaller one,
             so no need to check for larger ones) */
   
   J = 2;
   while (1)  {
      if (Prime[J] == 1)
         if (K % J == 0)  {
            Prime[K] = 0;
            return;
         }
      J++;
   }
   
   /* if we get here, then there were no divisors of K, so it is
      prime */
   Prime[K] = 1; 
}