[scilab-Users] Inexplicable result with scilab 5.0.2 and matrix multiplication

[Sylvestre Ledru]

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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
> > 
> > 
> > cd