[Maxima-bugs] [ maxima-Bugs-1309377 ] translated and untranslated 'is'

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Bugs item #1309377, was opened at 2005-09-30 06:56
Message generated for change (Comment added) made by rtoy
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Barton Willis (willisbl)
Assigned to: Nobody/Anonymous (nobody)
Summary: translated and untranslated 'is'

Initial Comment:
Consider:
(%i1) f(x) := (prederror : 'false, is(x <= -1))$

It seems that 'f' is OK:

(%i2) f(a);
(%o2) UNKNOWN
(%i3) f(-5);
(%o3) true
(%i4) f(5);
(%o4) false

After translation, f(a) --> error. This is bogus:

(%i5) translate(f)$
(%i6) f(a);
MACSYMA was unable to evaluate the predicate:
a+1>0

I think that the reason for the difference is that 
untranslated code evaluates predicates using 'mevalp' 
while translated code uses  'is-bool-check.'  

(%i7) build_info();
Maxima version: 5.9.1
Maxima build date: 7:34 9/24/2004
host type: i686-pc-mingw32
lisp-implementation-type: Kyoto Common Lisp
lisp-implementation-version: GCL 2.6.5

Barton

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>Comment By: Raymond Toy (rtoy)
Date: 2005-12-05 12:41

Message:
Logged In: YES 
user_id=28849

Actually, I think is-boole-check would be ok, if it called
mevalp_tr with a second arg of $prederror instead of T. 
Making this change indicates that mevalp_tr would return
$unknown.  But the translations for mleqp uses (not foo),
which causes it to return false when foo is $unknown.

Fixing that will cause the translated function to return the
same as the interpreted version.

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