[Maxima-bugs] [ maxima-Bugs-2913752 ] plot2d(a[x], [x,0,5]); STACK OVERFLOW

[SourceForge.net <no...@so...>]

Bugs item #2913752, was opened at 2009-12-13 17:13
Message generated for change (Comment added) made by crategus
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2913752&group_id=4933

Please note that this message will contain a full copy of the comment thread,
including the initial issue submission, for this request,
not just the latest update.
Category: Lisp Core - Plotting
Group: None
>Status: Pending
>Resolution: Wont Fix
Priority: 5
Private: No
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: plot2d(a[x], [x,0,5]); STACK OVERFLOW

Initial Comment:
Tested on Maxima 5.18.1, Maxima 5.19.2 (with clisp 2.47 and 2.48), Maxima 5.20.0 (with clisp 2.47 and 2.48) on Gentoo Linux amd64.
The same error occurs each time I try the following:

---------------------------------------------------------------------------------------------------------
Maxima 5.20.0 http://maxima.sourceforge.net
using Lisp CLISP 2.47 (2008-10-23)
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.
(%i1) a[0] : 3; a[n] := 2*a[n-1] -1;
(%o1)                                  3
(%o2)                         a  := 2 a      - 1
                               n       n - 1
(%i3) plot2d(a[x], [x,0,5]);

*** - Program stack overflow. RESET

[../src/eval.d:573] reset() found no driver frame (sp=0xb9d81210-0xb9d7ae40)
Exiting on signal 6
Aborted
---------------------------------------------------------------------------------------------------------

I know that you shouldn't try graphing discrete values like that but this is still a serious bug because it causes Maxima to crash and you lose all your session!.
I noticed that the same bug was reported previously (http://sourceforge.net/tracker/index.php?func=detail&aid=1533584&group_id=4933&atid=104933) and closed but it's still here.

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

>Comment By: Dieter Kaiser (crategus)
Date: 2009-12-13 18:32

Message:
The reported problem is not a problem of the plot function. The recursively
defined function can not handle floating point numbers which are needed for
the plot function.:

(%i1) a[0] : 3; a[n] := 2*a[n-1] -1;
(%o1) 3
(%o2) a[n]:=2*a[n-1]-1

We try to evaluate the function for a floating point number, but this is
not possible. The algorithm of the function loops endlessly:

(%i3) a[0.5];

*** - Program stack overflow. RESET

[/build/buildd/clisp-2.44.1/src/eval.d:527] reset() found no driver frame
(sp=0xbfd464a0-0xbfd407b0)
Exiting on signal 6
Aborted

The user defined function has to be improved to handle floating point
numbers to allow a plot. I think it is by the user to transfer a valid
function definition to the plot routine.

This problem is not related to the closed bug ID: 1533584. This bug seems
to be no longer present.

Setting the status to pending and the resolution to "wont fix".

Dieter Kaiser

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

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=104933&aid=2913752&group_id=4933