[Maxima-bugs] [ maxima-Bugs-1710604 ] simple_equal

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Bugs item #1710604, was opened at 2007-05-01 08:49
Message generated for change (Comment added) made by macrakis
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Category: Lisp Core
Group: None
Status: Open
Resolution: None
Priority: 1
Private: No
Submitted By: Barton Willis (willisbl)
Assigned to: Nobody/Anonymous (nobody)
Summary: simple_equal

Initial Comment:
simple_equal has a line of bogus and unreachable code (defined in mload of all places)

(defun $simple_equal (f g)
  "checks if equal up to simp flags"
  (cond	((quote-simple-equal f g))
	((quote-simple-equal g f))
	((and  (numberp f) (numberp g)
	       (or (eql f g))
	       (< (- f g) 1.0e-4))) <-- never happens

Also, simple_equal isn't documented. It's likely that
simple_equal isn't needed, but it's nice that it
(apparently) tests for equality without converting
CRE expressions to general form.


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>Comment By: Stavros Macrakis (macrakis)
Date: 2007-05-01 14:49

Message:
Logged In: YES 
user_id=588346
Originator: NO

The whole piece of code is weird.

The (or...) clause was presumably intended to be (or (eql f g) (< (- f g)
1.0e-4)), but that would be pretty ridiculous code, since it would make 0.0
== 1.0 but 1.0 /== 0.0. Fixing that with (abs (- f g)) would make 1.0e-5 ==
1.0e-100.

The rat case relies on the varlists being the same; is that desired?

   simple_equal(rat(x,x,y),rat(x,y,x)) => false.

The quote case is completely weird; not clear what it is trying to do:

   simple_equal( '('(y+1)), '('(x+2)) ) => true  (!!!!)

   simple_equal( '('(y+1)), '('(2)) ) => Lisp error

Simple_equal seems to be used by run_testsuite to see if actuals match
expected. It makes me a bit nervous in that role, but it makes me even more
nervous to see it exposed to users as a $-function.  Let's rename it to
simple-equal....

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