[Maxima-bugs] [ maxima-Bugs-1642851 ] notequal isn't negation of equal

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Bugs item #1642851, was opened at 2007-01-23 11:43
Message generated for change (Comment added) made by sf-robot
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Category: Lisp Core
Group: Includes proposed fix
>Status: Closed
Resolution: Fixed
Priority: 5
Private: No
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: notequal isn't negation of equal

Initial Comment:
The user documentation for 'notequal' says that
notequal(a,b) is the negation of equal(a,b).
It's not:

(%i1) is(equal(x,%i));
(%o1) false
(%i2) is(notequal(x,%i));

A putative fix is

(defun mnqp (x y)
  (let ((b (meqp x y)))
    (cond ((eq b '$unknown) b)
	  ((or (eq b t) (eq b nil)) (not b))
	  (t `(($notequal) ,x ,y)))))


With the exception of test in rtest_taylor 117, this change is OK with the testsuite 

  taylor(atan(1/sqrt(1-b))/sqrt(1-b),b,1,2)

With the proposed mneq code, test 117 asks
for the sign of b. If you answer pos (or neg), you
get a sign called on %i error. And it seems
that the asksign keeps some data about b
(it shouldn't).  With the old mnqp code,
test 117 fails with the  sign called on %i error,
but it doesn't go thru asksign. Advice?


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>Comment By: SourceForge Robot (sf-robot)
Date: 2007-02-08 19:20

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This Tracker item was closed automatically by the system. It was
previously set to a Pending status, and the original submitter
did not respond within 14 days (the time period specified by
the administrator of this Tracker).

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Comment By: Barton Willis (willisbl)
Date: 2007-01-25 14:19

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I see that in my initial post, I didn't include the (%o2); it should be
"`sign' called on an imaginary argument ..."

I applied the suggested fix; previously I commented out test 117
in rtest_taylor.

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Comment By: Barton Willis (willisbl)
Date: 2007-01-23 11:45

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I forgot to log in...

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