Subject: Relativistic addition of velocities in wxMaxima
From: laurent couraud
Date: Wed, 25 Sep 2013 11:01:49 +0200
2013/9/24 Raymond Toy <toy.raymond at gmail.com>
> >>>>> "laurent" == laurent couraud <l.couraud at gmail.com> writes:
>
> laurent> Hi everyone!
>
> laurent>
>
> laurent> i meet the following strange behavior:
>
> laurent>
>
> laurent> Maxima 5.31.0 http://maxima.sourceforge.net
> laurent> using Lisp GNU Common Lisp (GCL) GCL 2.6.8 (a.k.a. GCL)
> laurent> Distributed under the GNU Public License. See the file
> COPYING.
> laurent> Dedicated to the memory of William Schelter.
> laurent> The function bug_report() provides bug reporting information.
> laurent> (%i1) x^2;
> laurent> 2
> laurent> (%o1) x
> laurent> (%i2) subst(1e-3,x,%o1);
> laurent> (%o2)
> 0.0E-7
>
> Ah, this is probably a roundoff issue combined with a printing issue
> with gcl. What value is actually computed in %o2? Probably something
> like 0.999999e-6?
>
> (I don't have a gcl build right now.)
>
> Ray
>
>
(%i10) rat(%o2);
rat: replaced 0.0E-7 by 1/1000000 = 0.0E-7
1
(%o10)/R/ -------
1000000
(%i11) %o2*2;
(%o11) 2.0E-6
Then it seems the value is 1.0e-6. This is why I said it is
display/printing problem only.
Thank.
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