Re:

[Robert Bruce Findler <robby+@CMU.EDU>]

Excerpts from internet.listserv.info-mcl: 19-Oct-93  by David Evan
Jones@cats.uc 
> BUT, how about simple plotting of functions on a matrix?
> (Plotting the likes of f(x) = sin (x).)  Any code out 
> there?
> 
As far as printing out curves, I wrote some stuff to do that for testing
the spline code out in Numerical Recipies. Here it is:

(require 'quickdraw)

(defclass graph-window (window)
  ((x :accessor x :initform nil :initarg :x)
   (y :accessor y :initform nil :initarg :y)))

(defmethod view-draw-contents ((w graph-window))
  (flet ((scaler (xi max-xi min-xi win-max)
           (floor (pin-between (* (/ (- xi min-xi) (- max-xi min-xi))
win-max) -32768 32767))))
    (let* ((min-x (apply #'min (x w)))
           (max-x (apply #'max (x w)))
           (min-y (apply #'min (y w)))
           (max-y (apply #'max (y w)))
           (scaled-x (mapcar #'(lambda (x) (scaler x max-x min-x
(point-h (view-size w))))
                             (x w)))
           (scaled-y (mapcar #'(lambda (y) (scaler y max-y min-y
(point-v (view-size w))))
                             (y w))))
      (with-fore-color *light-blue-color*
        (move-to w 0 (scaler 0 max-y min-y (point-v (view-size w))))
        (line w (point-h (view-size w)) 0)

        (move-to w (scaler 1 max-x min-x (point-h (view-size w)))
                   (scaler 1 max-y min-y (point-v (view-size w))))
        (line-to w (scaler 1 max-x min-x (point-h (view-size w)))
                   (scaler -1 max-y min-y (point-v (view-size w))))
        (line-to w (scaler -1 max-x min-x (point-h (view-size w)))
                   (scaler -1 max-y min-y (point-v (view-size w))))
        (line-to w (scaler -1 max-x min-x (point-h (view-size w)))
                   (scaler 1 max-y min-y (point-v (view-size w))))
        (line-to w (scaler 1 max-x min-x (point-h (view-size w)))
                   (scaler 1 max-y min-y (point-v (view-size w))))

        (move-to w (scaler 0 max-x min-x (point-h (view-size w))) 0)
        (line w 0 (point-v (view-size w))))
      (move-to w 0 0)
      (mapcar #'(lambda (x y) (pen-normal w) 
                 (line-to w x y)
                 (move-to w x y)
;                 (set-pen-size w 2 2)
                 (line w 0 0)) 
              scaled-x scaled-y))))

(defun graph (x y)
  (make-instance 'graph-window :x x :y y))

(defun first-somethings (succ inital)
  #'(lambda (top)                         
      (labels ((f (x n) (if (equalp x n) (list n) (cons x (f (funcall
succ x) n)))))
        (f inital top))))

(setf (symbol-function 'nats-up-to) (first-somethings #'1+ 0))

; "pins" x between l and r
;input: numbers
;output: x if x is between l and r, and the closer one if it isn't.
(defun pin-between (x l r)
  (min r (max l x)))

(defun graph-function (x-min x-max f &optional (print-stuff? nil)
(resolution 100))
  (let* ((res (1- resolution))
         (x-vals (mapcar #'(lambda (x) (+ x-min (* (/ x res) (- x-max x-min))))
                        (nats-up-to res)))
         (y-vals (mapcar #'(lambda (x) (- (funcall f x))) x-vals)))
    (graph x-vals y-vals)
    (when print-stuff?
      (format t "last: ~a~%" (last y-vals)))))

It's a bit of a hodge podge, since I use a few functions from my utils
library, but I hope it's useful.
__________________________________________________________________________
Robby Findler                                               robby+@cmu.edu
Carnegie Mellon University    Pittsburgh, PA                (412) 681-4552