2.49.tex

\documentclass[a4paper,12pt]{article}
\usepackage{listings}
\lstset{language=Lisp}

\begin{document}
\begin{lstlisting}
(define o (make-vect 0 0))
(define j (make-vect 0 1))
(define i (make-vect 1 0))
(define k (make-vect 1 1))

(define outline
  (segments->painter
   (list (make-segment o j)
         (make-segment j k)
         (make-segment k i)
         (make-segment i o)))))

(define x-painter
  (segments->painter
   (list (make-segment o k)
         (make-segment j i))))

(define diamond
  (let ((m1 (make-vect 0 1/2))
        (m2 (make-vect 1/2 1))
        (m3 (make-vect 1 1/2))
        (m4 (make-vect 1/2 0))))
  (segments->painter
   (list (make-segment m1 m2)
         (make-segment m2 m3)
         (make-segment m3 m4)
         (make-segment m4 m1))))

(define wave
  (segments->painter
   (list
    (make-segment (make-vector 5/12 2/3)
                  (make-vector 1/3 5/6))
    (make-segment (make-vector 1/3 5/6)
                  (make-vector 5/12 1))
    (make-segment (make-vector 7/12 1)
                  (make-vector 2/3 5/6))
    (make-segment (make-vector 2/3 5/6)
                  (make-vector 7/12 3/3))
    (make-segment (make-vector 7/12 2/3)
                  (make-vector 2/3 2/3))
    (make-segment (make-vector 2/3 2/3)
                  (make-vector 1 1/2))
    (make-segment (make-vector 1 1/3)
                  (make-vector 7/12 1/2))
    (make-segment (make-vector 7/12 1/2)
                  (make-vector 0 2/3))
    (make-segment (make-vector 0 5/9)
                  (make-vector 1/2 1/3))
    (make-segment (make-vector 1/2 1/3)
                  (make-vector 0 4/9))
    (make-segment (make-vector 0 1/3)
                  (make-vector 5/12 1/2))
    (make-segment (make-vector 5/12 1/2)
                  (make-vector 1/3 7/12))
    (make-segment (make-vector 1/3 7/12)
                  (make-vector 1/6 1/2))
    (make-segment (make-vector 1/6 1/2)
                  (make-vector 0 2/3))
    (make-segment (make-vector 0 5/6)
                  (make-vector 1/6 7/12))
    (make-segment (make-vector 1/6 7/12)
                  (make-vector 1/3 2/3))
    (make-segment (make-vector 1/3 2/3)
                  (make-vector 5/12 2/3)))))
\end{lstlisting}
\end{document}