# [Maxima] 1/0? Why the error

Richard Hennessy rich.hennessy at verizon.net
Tue Apr 24 17:33:04 CDT 2012

```Carrying around undefined forms like this has been proposed before, but first think about what semantics you'd want around them.

Is 3/0 equal to 2/0? In that case, perhaps they should both simplify to 1/0.

Is 1/0 > 2345?

Is -1/0 < 1/0?

Is -1/0 the same as minf?

Is 1/0 - 1/0 equal to 0?  What is 3/0 - 2/0 ?

What is (3/0)*0?  Should that simplify to 3? to 1? Or just remain unsimplified?  If unsimplified, what use is it?

Keeping terms like this unsimplified is of some use to programmers who write their own simplification rules taking the current problem context into account. That is why I would like to keep terms like this from blowing up Maxima before my program that I might have written can even get the input.

Rich

On Tue, Apr 24, 2012 at 17:27, Richard Hennessy <rich.hennessy at verizon.net> wrote:

If you type in :

(%i5) kill(all);
(%o0) done
(%i1) 3/4;
(%o1) 3/4
(%i2) 3/2;
(%o2) 3/2
(%i3) 3/1;
(%o3) 3
(%i4) 3/0;
expt: undefined: 0 to a negative exponent.
-- an error. To debug this try: debugmode(true);

Since Maxima is not trying to compute the answer, it just simplifies the input in these cases, why the error?  Would it be better if you could get the unsimplified form back?

(%i5) 3/0;
(%o5) 3/0

Rich

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