[Maxima-bugs] [ maxima-Bugs-1691703 ] float(ceiling(...)) sometimes returns float, sometimes int

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

Bugs item #1691703, was opened at 2007-03-30 19:19
Message generated for change (Tracker Item Submitted) made by Item Submitter
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1691703&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 - Simplification
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Stavros Macrakis (macrakis)
Assigned to: Nobody/Anonymous (nobody)
Summary: float(ceiling(...)) sometimes returns float, sometimes int

Initial Comment:
float(ceiling(log(9)/log(2))) => 3.0 (a float)
float(ceiling(log(8)/log(2))) => 3   (an integer)

This is because
  ceiling(log(9)/log(2))=4
but
  ceiling(log(8)/log(2)) => ceiling(log(8)/log(2))
and only simplifies to a number when the argument is evaluated as a float.

float(ceiling(log(2^80)/log(2))) =>   80 (an integer)
float(ceiling(log(2^80-1)/log(2))) => 80.0 (a float)

Shouldn't float(...) always be returning a float if it's returning a number?  I think the problem is that it assumes that if f(x) simplifies to a number, and x is a float, then f(x) is a float.

I think it makes sense for ceiling(2.3) => 3 (not 3.0), so the problem seems to be in float, not in simp-ceiling.

You could argue that ceiling should do a better job in the first place, but that's an orthogonal issue, and in any case it will never handle all possible cases.



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

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1691703&group_id=4933