// Verilog
// (C) 2001 by M. Thole

module apfel;
   parameter itmax = 10,	// max iterations
	     rad = 4.0,		// test radius
	     resolution = 500,	// number of points per line
	     xmin = -2.25,	// min x value
	     xmax = 0.75,	// max x value
	     ymin = -1.5,	// min y value
	     ymax = 1.5;	// max y value
   integer result;
   real x, y;
   
   // This function calculates the mandelbrot iteration for a given
   // complex point of the z plane (re, im)
   
   function integer iterate;
      input re, im, itmax, rad;
      integer i, itmax;
      real    re, im, xnew, ynew, x, y, xq, rad;
      
      begin
	 i = 0;
	 x = 0.0;
	 y = 0.0;
	 
	 while ((i < itmax) && (x*x + y*y < rad))
	    begin
	       xnew = x*x - y * y + re;
	       ynew = 2.0 * x * y + im;
	       x = xnew;
	       y = ynew;
	       i = i+1;
	    end
	 iterate = i;
      end
   endfunction // iterate

   initial
      begin
	 for (y = ymin; y <= ymax; y = y + (ymax-ymin)/resolution)
	    begin
	       for (x = xmin; x <= xmax; x = x + (xmax-xmin)/resolution)
		  begin
		     result = iterate(x, y, itmax, rad);
		     $write("%c", (result % 2) ? " " : "#");
		  end
	       $write("\n");
	    end
      end
   
endmodule // apfel