Probably not a bug, at least not a bug in Maxima.
5.1 is a hardware floating point number. So is 3.2
Changed fpprec does not affect this arithmetic.
try bfloat(51/10) + bfloat(32/10).
By the time you type in 5.1, you have already lost the exactness you would
like.
The same thing should happen in GCL. in fact (+ 5.1 3.2) comes out
8.3000000000000007
Though in allegro common lisp, (+ 5.1 3.2) comes out as 8.3
This may have to do with decimal-to-binary and binary-to-decimal conversion
errors.
RJF
> -----Original Message-----
> From: maxima-bounces at math.utexas.edu
> [mailto:maxima-bounces at math.utexas.edu] On Behalf Of sen1 at math.msu.edu
> Sent: Saturday, August 26, 2006 2:58 PM
> To: maxima at math.utexas.edu
> Subject: Serious bug
>
> Hello,
> I have not migrated to the "bug reporting list" yet. If
> this is more
> appropriately put there, I'll be happy to do that.
>
> In Win-XP xmaxima 5.9.3.99rc2
>
> (%i1) 5.1 + 3.2;
> (%o1) 8.300000000000001
> (%i2) fpprec: 30;
> (%o2) 30
> (%i3) 5.1 + 3.2;
> (%o3) 8.300000000000001
>
> I checked this in v. 5.9.3 and the same problem occurs,
> except that the last digit when done in hihg precision is a "?"
> I did the same test in Linux and the problem is NOT there. The
> result is 8.3 as it should be.
>
> I think others should try this to see if it occurs on their systems.
>
> I tried this on two different Win-XP machines, so it is not
> likely to ba a hardware problem.
>
> I hope others try this to verify whether these are problems
> with my installation of they exist everywhere.
>
> -sen
>
>
>
> --------------------------------------------------------------
> -------------
> | Sheldon E. Newhouse | e-mail:
> sen1 at math.msu.edu |
> | Mathematics Department |
> |
> | Michigan State University | telephone: 517-355-9684
> |
> | E. Lansing, MI 48824-1027 USA | FAX: 517-432-1562
> |
>
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