[Maxima-bugs] [ maxima-Bugs-1294744 ] dot-operator precedence 110 ?

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Bugs item #1294744, was opened at 2005-09-18 13:11
Message generated for change (Comment added) made by robert_dodier
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Category: Lisp Core
>Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: van_Nek (van_nek)
Assigned to: Nobody/Anonymous (nobody)
Summary: dot-operator precedence 110 ?

Initial Comment:
-------------------------------------------------------------

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

-------------------------------------------------------------
(C54) a*[v1,v2] . b*[w1,w2];
(D54) 			  [a*w1, a*w2]*([v1, v2] . b)
(C55) :lisp $C54
((MTIMES) $a ((MNCTIMES) ((MLIST) $v1 $v2) $b) ((MLIST)
$w1 $w2))
(C55) :lisp(describe 'mnctimes)
MNCTIMES - internal symbol in MAXIMA package
...
 property RBP:
   109
 property LBP:
   110
...
(C55) :lisp(describe 'mtimes)
MTIMES - internal symbol in MAXIMA package
...
 property RBP:
   120
 property LBP:
   120
...

I regard this information as the operator precedence,
or am I wrong?
If this is the precedence, D54 should be the result of
the following D55.

(C55) (a*[v1,v2]) . (b*[w1,w2]);
(D55) 			     a*b*v2*w2 + a*b*v1*w1

Can someone explain, if the rbp and lbp values are the
operator precedence values and what the correct value
for dot is.

Volker van Nek

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>Comment By: Robert Dodier (robert_dodier)
Date: 2005-09-23 23:38

Message:
Logged In: YES 
user_id=501686

LBP and RBP are indeed operator precedence values (see
"Syntax" under "Expressions",
http://maxima.sf.net/docs/manual/en/maxima_toc.html).
However it is the LBP and RBP of the symbols $. and $* which
are relevant to parsing input expressions; the parser sees
only the atoms in the input stream, not MNCTIMES or MTIMES.  

LBP and RBP for input symbols are defined in
src/nparse.lisp, which establishes () that "." has higher
precedence than "*". However, for the purposes of display
(essentially to determine which subexpressions need
parentheses), src/grind.lisp establishes precedence for
operators MNCTIMES, MTIMES, etc. The list in src/grind.lisp
is out-of-date with respect to src/nparse.lisp -- in
particular, "." has lower precedence than "*" there. 

The list in src/grind.lisp should be changed to have the
same precedence values as in src/nparse.lisp.

Whether "." should have higher or lower or the same
precedence as "*", I don't know, and it is not immediately
relevant, so I'm going to leave that alone.

----------------------------------------------------------------------

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