anchor.diff:              (reset-trans-matrix))))
   
         ;; draw graph
  +      (stroke)
         (set-line-width 2)
  +      
         (loop for p in vals
            for c in colors
            for s in styles do
  -           (progn
  -             (apply #'set-source-rgb c)
  -             (set-dash 1 (cond ((eq s :solid) (make-array 0))
  -                               ((eq s :dashed) (list 6 6))
  -                               ((eq s :dash-dot) (list 12 6 6 6))
  -                               ((eq s :long-dash) '(24 6))
  -                               (t (make-array 0)))))
  -           (loop for (x y) in p
  -              as flag = t then nil
  -              do (if flag
  -                     (move-to (tx x) (ty y))
  -                     (line-to (tx x) (ty y))))
  -           (stroke))
  +           (apply #'set-source-rgb c)
  +           (if (eq s :marker-circle)
  +               (progn
  +                 (set-dash 1 (make-array 0))
  +                 (loop for (x y) in p
  +                    do (arc (tx x) (ty y) 5 0 (+ pi pi))
  +                      (fill-path)))
  +               (progn
  +                 (set-dash 1 (cond ((eq s :solid) (make-array 0))
  +                                   ((eq s :dashed) (list 6 6))
  +                                   ((eq s :dash-dot) (list 12 6 6 6))
  +                                   ((eq s :long-dash) '(24 6))
  +                                   (t (make-array 0))))
  +                 (loop for (x y) in p
  +                    as flag = t then nil
  +                    do (if flag
  +                           (move-to (tx x) (ty y))
  +                           (line-to (tx x) (ty y))))
  +                 (stroke))))
       
         ;; draw legend
         (when legend
  
positive.code:            :plot2d
             :plot/a
             :plot/xy
             :trend
             :polar-r
             :polar-ra
  
negative.code:             (y (append ay y)))
          (setf (accum gen) (list x y))
          (plot+xy x y (theme gen) (aspect gen) (legend gen) (get-labels gen) (width gen) (filename gen) (get-format gen))))))
  
  (defmethod generate ((gen polar-xy) funcs)
    "Plot polar functions of X and Y. Each `FUNCS` takes one argument, theta. Each curve should be a pair of functions."
    (flet ((func/r (f)
  