#include "genlib.h"

/*determines the greatest prime factor of an integer*/
int maxfactor(int n)
{
  int test_fact(int *pnum, int fact, int *pmaxfac);
  int lnum, fact;
  int maxfac;

  maxfac = 1;
  lnum = n;

  if ( lnum != 0 && lnum != 1 ) {
    fact = 2;
    if ( test_fact( &lnum, fact,&maxfac)) {
      fact = 3;
      if ( test_fact( &lnum, fact,&maxfac)) {
	fact = 5;
	for (;;) {
	  if (!test_fact( &lnum, fact,&maxfac))
	    break;
	  fact += 2;
	  if (!test_fact( &lnum, fact,&maxfac))
	    break;
	  fact += 4;
	}
      }
    }
    if ( lnum != 1 ) {
      if (lnum > maxfac)
	maxfac = lnum;
    }
  }
  return (maxfac);
}