/* Sub- and main programs, fields class nr = 3, d = 0 mod 4,  T J Dekker, 2007.	*/
	/* Draws pictures of prime numbers (red) and prime non-principal ideals (green)	*/
	/* obtained by dividing by non-principal ideal of norm 2.						*/
	/* main program moreover uses subprograms from files quadchar.c and sievquad.c.	*/
	/* DrawUnit.c defines 'Initialize' and, by inclusion, drawing subprograms used.	*/ 

					
	/*    class nr == 3, bynorm 3 is not norm of principal ideal   */ 
	int radicand[]= {79, 142, 223, 254, 326, 359, 0}; 
	int bynorm, shift;																     

	void showitem()
	{	  char it[30]; int i, k; int natp[] = {2, 3, 5, 7, 11, 13};
		  for (i = 0; i < 6 && qchar[natp[i]] <= 0; i++) ; bynorm = natp[i];
		  for (k = 0; k < 100 && QNORM(k, 1) % bynorm != 0; k++) ; shift = k;  
		  RGBForeColor(&blue); sprintf(it, "    prime numbers    ");   drawstring(it);
		  RGBForeColor(&gray); sprintf(it, "    units    ");           drawstring(it);
		  RGBForeColor(&green);   sprintf(it, "    prime ideals ");    drawstring(it);
		  RGBForeColor(&red); sprintf(it, "by norm %d shift %d", bynorm, shift); 
		  drawstring(it); RGBForeColor(&black);
	}	  /* end showitem */
	
	void drawitem(int x, int y, int norm)
	/* draws prime and unit of field for discriminant discr % 4 == 0 	*/
	{     if (norm >= maxnorm) drawprim(x, y, &black);				/*  too large  */
	      else if (norm == bynorm) drawprim(x, y, &black); 		/*  reject bynorm  */
	      else if (inset(norm, prinorm)) drawprim(x, y, &blue);   /*  primes blue  */
	      else if (norm == 1) drawprim(x, y, &gray);           /*  draw unit gray  */
	      else    		  		/* draw non-principal ideals in green or red color */
				if (norm % bynorm == 0 && inset(norm/bynorm, prinorm))
	            {	 if ((x + shift * y) % bynorm != 0) drawprim(x, y, &green);
	           		 else drawprim(x, y, &red);
	      		}
	}     /* end drawitem */