Re: how to detect division by zero?

[Roland Orre]

On Tue, 2004-01-20 at 15:17, Rouben Rostamian wrote:
> How does one detect the result of a division by 0.0 in guile?

You could define the values of the not_a_numbers and test with those.
In guile 1.7 symbols for these values are already predefined, so you
could use the following definitions to be future compatible. However,
I just found that (/ 0.0 0.0) can not be tested neither in 1.6 or 1.7.

(define +inf.0 (/ 1.0 0.0))
(define -inf.0 (/ -1.0 0.0))
(define +nan.0 (/ 0.0 0.0))

guile-user> (= +inf.0 (/ 100.0 0.0))
#t
guile-user> (= -inf.0 (/ -100.0 0.0))
#t

Of some reason does the followoing return false
guile-user> (= +nan.0 (/ 0.0 0.0))

/Roland