Exercise 2.10: off by one

[Meretan]

Interval boundaries should be checked as well:

#;1> (div-interval (make-interval 1 2) (make-interval 22 0))

Error: (/) division by zero
1.0
0

        Call history:

        <eval>    [div-interval] (lower-bound y)
        <eval>    [lower-bound] (min (car i) (cdr i))
        <eval>    [lower-bound] (car i)
        <eval>    [lower-bound] (cdr i)
        <eval>    [div-interval] (mul-interval x (make-interval (/ 1.0 (upper-bound y)) (/ 1.0 (lower-bound y))))
        <eval>    [div-interval] (make-interval (/ 1.0 (upper-bound y)) (/ 1.0 (lower-bound y)))
        <eval>    [div-interval] (/ 1.0 (upper-bound y))
        <eval>    [div-interval] (upper-bound y)
        <eval>    [upper-bound] (max (car i) (cdr i))
        <eval>    [upper-bound] (car i)
        <eval>    [upper-bound] (cdr i)
        <eval>    [div-interval] (/ 1.0 (lower-bound y))
        <eval>    [div-interval] (lower-bound y)
        <eval>    [lower-bound] (min (car i) (cdr i))
        <eval>    [lower-bound] (car i)
        <eval>    [lower-bound] (cdr i) <--