2.11.tex

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

\begin{document}
\begin{lstlisting}
(define (mul-interval x y)
  (let ((l1 (lower-bound x))
        (l2 (lower-bound y))
        (u1 (upper-bound x))
        (u2 (upper-bound y)))
    (cond ((and (>= l1 0) (>= l2 0))
           (make-interval (* l1 l2) (* u1 u2)))
          ((and (>= l1 0) (<= u2 0))
           (make-interval (* u1 l2) (* u2 l1)))
          ((and (>= l1 0) (> u2 0))
           (make-interval (* u1 l2) (* u1 u2)))
          ((and (<= u1 0) (<= u2 0))
           (make-interval (* u1 u2) (* l1 l2)))
          ((and (<= u1 0) (>= l2 0))
           (make-interval (* u2 l1) (* u1 l2)))
          ((<= u1 0)
           (make-interval (* u2 l1) (* l1 l2)))
          ((>= l2 0)
           (make-interval (* u2 l1) (* u1 u2)))
          ((<= u2 0)
           (make-interval (* u1 l2) (* l1 l2)))
          (else
           (make-interval (min (* u1 l2)
                               (* u2 l1))
                          (max (* l1 l2)
                               (* u1 u2)))))))
\end{lstlisting}
\end{document}