anchor.diff:  								   (ywin 0.5)
   								   (zoom 10.0)
   								   (count 10))
  +  "Generate a series of Mandelbrot Set images, zooming into the location xloc,yloc. The initial window width and height are given by xwin and ywin.  The number of images is given by count. Zoom specifies how much to zoom in for each frame.  The file-name-format parameter specifies a format string that can be used in the call (format t file-name-format i) to generate a file name for the ith file in the sequence - typically something like image~a.png."
     (dotimes (i count)
   	(let ((cxwin (/ xwin (expt zoom i)))
   		  (cywin (/ ywin (expt zoom i))))
   	  (format t "window: ~a ~a~%" cxwin cywin)
  -	  (make-mandelbrot-window :file-name (format nil file-format i)
  +	  (make-mandelbrot-window :file-name (format nil file-name-format i)
   							  :width width :height height
   							  :xloc xloc
   							  :yloc yloc
  
positive.code: 		 ((unsigned-byte 32) (unsigned-byte 32) double-float double-float )) map-val))
  
  (defun set-pixel (img x y r g b)
    (setf (aref img x y 0) r)
    (setf (aref img x y 1) g)
    (setf (aref img x y 2) b))
  
  (defun increment-pixel (img x y)
    (if (< (aref img y x 0) 255)
  	  (progn 
  		(incf (aref img y x 0))
  
negative.code: 			  (let ((xxx (* (- xx xxmin) xinc))
  					(yyy (* (- yy yymin) yinc)))
  				(if (and (< xxx width) (< yyy height))
  					(increment-pixel img (truncate xxx) (truncate yyy)))))))
  
  	(with-open-file (output file-name :element-type '(unsigned-byte 8) :direction :output :if-exists :supersede)
  					(png:encode img output))))
  