Add exercise 2.9

2022-11-05 12:51:15 +01:00 · 2022-11-05 12:51:15 +01:00 · 121cad7707
commit 121cad7707
parent d7bcd52fd0
1 changed files with 7 additions and 0 deletions
--- a/chapter2.lisp
+++ b/chapter2.lisp
@ -90,3 +90,10 @@
  (make-interval (- (lower-bound b) (lower-bound a))
 		 (- (upper-bound b) (upper-bound a))))

+;; Exercise 2.9
+(defun width-interval (x)
+  "Calculate width of an interval as half of the distance between lower
+and upper bound."
+  (/ (- (upper-bound x) (lower-bound x))
+     2.0))
+