> From: Jan Wedekind <[email protected]>
> Subject: bug#29387: Guile-2.2.2 complex numbers edge case
> Date: 21 Nov 2017 23:09:57 GMT+1
> To: [email protected]
> Reply-To: Jan Wedekind <[email protected]>
>
>
> Hi,
> I think I encountered a bug in the numerical stack.
> i times i should equal -1:
>
> (equal? -1 (* 0+i 0+i))
> ; #f
>
> i times i plus one is zero (which is correct):
> (zero? (+ (* 0+i 0+i) 1))
> ; #t
>
> Regards
> Jan
In Guile 0+i and (* 0+i 0+i) are inexact numbers, but -1 is exact. That's why
equal? fails.
You can check that either of
(equal? -1.+0. (* 0+i 0+i))
or
(= -1 (* 0+i 0+i))
return true, as expected.
I don't know if the fact that Guile doesn't have exact complex numbers could be
considered a bug. AFAIR none of the standards require them to be implemented.
On the other hand I just checked and both Racket and Chez seem to have them,
so...
regards
Daniel
