[Maxima-bugs] [ maxima-Bugs-1852344 ] sort(rat(...)) internal error

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Bugs item #1852344, was opened at 2007-12-17 06:52
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Stavros Macrakis (macrakis)
Assigned to: Nobody/Anonymous (nobody)
Summary: sort(rat(...)) internal error

Initial Comment:
sort(rat([x=1,y=1])) => fatal error

Maxima 5.13.0 GCL 2.6.8 Windows XP


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Comment By: Nobody/Anonymous (nobody)
Date: 2007-12-18 07:07

Message:
Logged In: NO 

Re: e: rat(x=1)$ ratp(e) => false; ratp(lhs(e)) => true

This is as designed (though it may be surprising that ratp(rat(...)) isn't
always true.  After all, there is no way to represent relational operators
in CRE form.

> ratdisrep doesn't convert the left and right sides of e to general
form.

This is normal.  ratdisrep only disreps the top level. You need
totaldisrep to disrep all the way down.

You get the same thing with rat([x,y]).  Which brings up another bug...:

   rat([(x^2-1)/(x-1)]) => [x-1]

but

   rat({(x^2-1)/(x-1)}) => {(x^2-1)/(x-1)}

This is precisely *because* ratp(rat({x})) = true!


(%i54) rat([(x^2-1)/(x-1)]);
Evaluation took 0.00 seconds (0.00 elapsed)
(%o54)/R/                                         [x + 1]



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Comment By: Barton Willis (willisbl)
Date: 2007-12-18 04:32

Message:
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Originator: NO

I think there is a bug / weirdness with the way rat interacts with =
expressions.

(%i1) e : rat(x=1)$

We have ratp(e) --> false and ratp(first(e)) --> true.

(%i2) ratp(e);
(%o2) false

(%i3) ratp(first(e));
(%o3) true

Also, ratdisrep doesn't convert the left and right sides of e to general
form.

(%i4) e : ratdisrep(e)$
(%i5) ratp(first(e));
(%o5) true



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Comment By: Stavros Macrakis (macrakis)
Date: 2007-12-17 11:10

Message:
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Originator: YES

This appears to come from orderlessp(rat(a=1),rat(b=1)) => fatal error

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