# [Maxima] bug in 'is' ?

Stavros Macrakis macrakis at alum.mit.edu
Mon Feb 20 13:35:47 CST 2012

```I agree.

Though I was sort of hoping someone would come up with a solution which
would know that "Louis VIII" < "Louis IX",  "4/7"< "4/5", and "4/4/2000" <
"3/3/2001"  :-)

-s

On Mon, Feb 20, 2012 at 12:51, Robert Dodier <robert.dodier at gmail.com>wrote:

> Well, I'm inclined to say that numbers and strings are incomparable
> under "<", so is(1 < "a") should be an error (4 below).
>
> The convenience of (2) or (3) is greatly outweighed by the confusion
> they'll cause. (I know you are not advocating these, Stavros.)
>
> Not sure about (1). It's not too bad, although the choice of strings
> before numbers or numbers before strings is arbitrary and therefore
> makes it a little more difficult to understand.
>
> I guess I don't see a reason that all kinds of object in Maxima
> should be comparable under "<". So we need not try too hard
> to make strings and numbers comparable.
>
> best
>
> Robert Dodier
>
>
> On 2/20/12, Stavros Macrakis <macrakis at alum.mit.edu> wrote:
>
> > Using the same operator for string and number comparison naturally poses
> > the question of mixed types.  Some possibilities:
> >
> > (1) All numbers are smaller than all strings (or vice versa) -- I think
> > this is what orderlessp does
> > (2) Convert numbers to strings, then compare.
> >     Some systems do this for *all* mixed operations, so that 3+"5foo" =>
> > "35foo" (concatenation)
> >     Problem: 3 < 20  and 20 < "3", but "3" == 3; also "3e3" < "4e2", but
> > 3e3 > 4e2
> > (3) Convert strings to numbers, then compare.
> >     Some systems do this for *all* mixed operations, so that 3+"5foo" =>
> 8
> >     Problem: what do you do with "foo"?  with "3foo"? with "foo3"? with
> > "4/4/2010"?
> > (4) Undefined/Error
> >
> > Since Maxima can manipulate symbolic inequalities, it's especially
> > important that the system be consistent.  I think the only consistent
> > possibilities are (1) and (4).  I would say: if you want orderlessp
> > behavior, use orderlessp.
> >
> >              -s
>
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