Re: [dev-serveez] complex guile server test

[stefan]

Hello again,

  playing around with Mandelbrot-Algorithm I got the following Guile
code bit:

======= 8< == mandelbrot.scm ======================================

;; Mandelbrot set

(define epsilon 1e-4)
(define MaxIteration (* 1 1024))
(define Colors MaxIteration)
(define xRes 100)
(define yRes 100)
(define Start (make-rectangular -2 -2))
(define End   (make-rectangular +2 +2))

(define (near z1 z2)
  (and (< (abs (real-part (- z2 z1))) epsilon)
       (< (abs (imag-part (- z2 z1))) epsilon)))

(define (iterateMandel z)
  (let* ((old-z z) (done #f) (i 0) (result (- MaxIteration 1)))
    (do ((i 0 (+ i 1)))
        ((or done (>= i MaxIteration)))
      (set! z (+ z (* z z)))
      (if (near z old-z)
          (set! i (- MaxIteration 1)))
      (if (> (magnitude z) 2)
          (begin
            (set! done #t)
            (set! result i)))
      (set! old-z z))
    result))

(define (doMandel z1 z2 x-res y-res colors)
  (let* ((x-diff (real-part (- z2 z1))) 
         (y-diff (imag-part (- z2 z1)))
         (x-ratio (/ x-diff x-res))
         (y-ratio (/ y-diff y-res))
         (x 0)
         (y 0)
         (z z1)
         (i 0) (n 0)
         (vector (make-vector (* x-res y-res))))

    (set! y-diff (* 0+1i y-diff))
    (set! y-ratio (* 0+1i y-ratio))
    (set! z (+ z (+ (/ y-ratio 2) (/ x-ratio 2))))
    (do ((x 0 (+ x 1)))
        ((>= x x-res))
      (do ((y 0 (+ y 1)))
          ((>= y y-res))
        (set! i (iterateMandel z))
        (vector-set! vector n (modulo i colors))
        (set! n (+ n 1))
        (set! z (+ z y-ratio)))
      (set! z (- (+ z x-ratio) y-diff)))
    vector))

(define (pretty i)
  (let ((str ""))
    (if (< i 10)
        (set! str "0")
        (if (< i 100)
            (set! str "")))
    (display str) (display i)))

(define (printMandel Mandel x-res y-res)
  (let* ((x 0) (y 0))
    (display "Mandelbrot:\n")
    (do ((y 0 (+ y 1)))
        ((>= y y-res))
      (do ((x 0 (+ x 1)))
          ((>= x x-res))
        (pretty (vector-ref Mandel (+ (* x-res y) x)))
        (display " "))
      (newline))))

(define t (current-time))
(define Mandel (doMandel Start End xRes yRes Colors))
(display (- (current-time) t)) (display " seconds --- ")

(printMandel Mandel xRes yRes)

======= >8 ==========================================================

Martin: Is this any good/acceptable Guile style?  When looking at the
*.scm files in ice-9 I start shivering.  The above code is rather C
thinking and straight forward.  Could you please comment?

Thanks in advance,
        address@hidden