[scilab-Users] Inexplicable result with scilab 5.0.2 and matrix multiplication
Sylvestre Ledru
sylvestre.ledru at inria.fr
Mon Oct 13 23:52:23 CEST 2008
Grr, I forgot that bug. Thanks for digging it up.
Sylvestre
Le lundi 13 octobre 2008 à 23:48 +0200, François Vogel a écrit :
> Looks like this one:
>
> http://bugzilla.scilab.org/show_bug.cgi?id=2647
>
> Francois
>
>
> Sylvestre Ledru said on 13/10/2008 23:40:
> > Hello,
> >
> > It is most probably a bug in the printing functions... I can reproduce
> > it with the binary (ie not compiled on my computer) but I can't on my
> > dev version (compiled with gfortran 4.3.1)
> > Once, we had a simular bug caused by a bug in gfortran. Maybe it is a
> > regression.
> >
> > Thanks for pointing this out.
> > Sylvestre
> >
> > Le lundi 13 octobre 2008 à 23:32 +0200, Christoph Dittmann a écrit :
> >> Hi,
> >>
> >> I've got a problem with scilab 5.0.2. It seems to print certain values
> >> wrong. The following example shows the problem:
> >> -->M = [1,2;3,2]; C = M^(-1)*M
> >> C =
> >>
> >> 2. 1.110D-16
> >> 1.110D-16 2.
> >>
> >> This is what I get with scilab 5.0.2 on Ubuntu 8.04 (x86) using the
> >> precompiled version from http://www.scilab.org/download/ . My problem
> >> are the 2's on the diagonal since I've no idea where they come from.
> >>
> >> With scilab 4.1.2, the one from the Ubuntu 8.04 repository, I get what I
> >> expect:
> >> -->M = [1,2;3,2]; C = M^(-1)*M
> >> C =
> >>
> >> 1. 1.110D-16
> >> 5.551D-17 1.
> >>
> >>
> >> Some further calculations with scilab 5.0.2 show that the problem seems
> >> to lie in the printing of the result and not its actual numerical value:
> >> -->x = C(1,1)
> >> x =
> >>
> >> 2.
> >> -->x * 2
> >> ans =
> >>
> >> 2.
> >> -->x + 0.01
> >> ans =
> >>
> >> 1.01
> >>
> >>
> >> Could that be a bug or did I just miss something crucial?
> >>
> >>
> >> Thanks,
> >> Christoph
> >
> >
> >
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