Edit detail for #83 Bug 5977 1::DMP([x],FRAC INT)::POLY FRAC INT ==> 0 revision 9 of 13

William Sit  wrote:
 > Martin wrote:
 > 
 > Thanks for investigating further.
 >  
 > > it might be that there is an error in mainVariable$SMP, but more likely, the
 > > bug is earlier in the history. mainVariable$SMP is called from coerce$POLY,
 > > interestingly without checking that the result of mainVariable might be
 > > "failed".
 > 
 > Shouldn't that mean coerce$POLY should be fixed to check the "failed" case?


Sorry, my mistake. coerce$POLY checks itself whether there is a variable or 
not:
 > Which coerce$POLY is that?


the coerce operation in the POLY domain:
 > > (66) -> 1::DMP([x],FRAC INT)::POLY FRAC INT
 > > 
 > >    coerce$POLY
 > >    mainVariable1$SMP
 > >    mainVariable3$SMP
 > >    mainVariable4$SMP
 > >  LISP output:
 > > 1
 > >    coerce4$POLY
 > >    1
 > >    coerce5$POLY
 > >    coerce6$POLY
 > >    (66)  0
 > >                           Type: Polynomial Fraction Integer

 > > Is there a way to find out what exactly the variable p in mainVariable
 > > contains?
 > > 
 > use p$Rep  ? or trace boot.


I'm pretty sure that the coercion to from DMP to POLY fails, without signalling 
an error, just like you could always do a "pretend". This would also explain 
(66)
Note that it is not possible to coerce a DMP or a UP or anything the like to a 
POLY in compiled code! Unfortunately I don't know where these interpreter 
coercions are coded. In any case, I'm convinced that they should be coded in 
the Algebra, not in the interpreter:
 > Now p is declared in multpoly.spad as Union(R, VPoly).
 > So the code mainVariable p seems to be correct, but your debug info
 > 
 > > (65) -> 1::DMP([x],INT)::POLY INT
 > > 
 > >    coerce$POLY
 > >    mainVariable1$SMP
 > >    mainVariable3$SMP
 > >    mainVariable4$SMP
 > > 
 > >    >> System error:
 > >    Caught fatal error [memory may be damaged]
 > > 
 > > protected-symbol-warn called with (NIL)
 > 
 > suggests that when 1$DMP([x], INT) is passed on to coerce$(POLY INT) and then to
 > mainVariable$SMP as p, it is recognized as "case VPoly". So that must be where
 > the bug is, in coerce$(POLY INT).


Note that coerce$POLY only coerces to OutputForm?... No internal stuff done 
there. That's why I'm sure that it is an interpreter bug.


the original complaint --Tim Daly,  Tue, 15 Feb 2005 20:39:05 -0600 reply
Problem:
 (1) -> a:=1::DMP(['x],INT)

   (1)  1
               Type: DistributedMultivariatePolynomial([x],Integer)
 (2) -> a::POLY INT

   >> System error:
   Caught fatal error [memory may be damaged]

 protected-symbol-warn called with (NIL)
 (2) -> variables(a)

   (2)  []
                                           Type: List OrderedVariableList [x]
 (3) -> a::INT::POLY INT

   (3)  1
                                Type: Polynomial Integer

 (4) -> 1::DMP([x],INT)::POLY INT

   >> System error:
   Caught fatal error [memory may be damaged]

 protected-symbol-warn called with (NIL)

 (5) -> 1::DMP([x],INT)::DMP([y],INT)

   (5)  1
               Type: DistributedMultivariatePolynomial([y],Integer)

 and 

 1::POLY INT :: DMP([x],INT) 
 x::DMP([x],INT)::POLY INT
 1::DMP([x,y],INT)::POLY INT 
 1::EXPR INT:: POLY INT 
 1::UP(x,INT)::POLY INT

 and (surprise!) even

 1::DMP([x],INT)::POLY FRAC INT

 all worked!


This bug also exists in the NAG version, where the first (2) would give "Memory
access violation detected".  Two observations: (a) the coercion in (2), shows
the interpreter does not follow the two steps in (3); and (b) the problem is
specific to POLY INT. It may also have to do with the second (2), and my
suspicion is that it has to do with a combination of the interpreter, POLY, DMP,
INT, no variables, and may be POLYLIFT or MLIFT.
Tim: can you do a boot trace of (4) and compare that with any of the others that
work?
fixed in FriCAS? --kratt6,  Thu, 20 Dec 2007 01:45:47 -0800 reply
Status: open => fix proposed 

... --gdr,  Wed, 21 May 2008 02:23:07 -0700 reply
Status: fix proposed => fixed somewhere 

no patch available
fixed? --Bill Page,  Wed, 21 May 2008 07:49:14 -0700 reply


... --gdr,  Wed, 21 May 2008 08:40:05 -0700 reply
Status: fixed somewhere => open 

Not really fixed.  sorry.
From wh-sandbox --japp,  Fri, 05 Sep 2008 20:45:10 -0700 reply
http://axiom.svn.sourceforge.net/viewvc/axiom/branches/wh-sandbox/src/interp/i-coerfn.boot.pamphlet?r1=263&r2=636&view=patch

Error: export AXIOM=/usr/local/lib/open-axiom/x86_64-unknown-linux/1.2.0-2008-05-25; export ALDORROOT=/usr/local/aldor/linux/1.1.0; export PATH=PATH; export HOME=/var/zope2/var/LatexWiki; ulimit -t 240; $AXIOM/bin/AXIOMsys < /var/zope2/var/LatexWiki/5249788430944991929-25px.axm