Re: polyfit test fails

[Marco Atzeri]

--- Sab 23/5/09, Ben Abbott <address@hidden> ha scritto:

> Da: Ben Abbott <address@hidden>
> Oggetto: Re: polyfit test fails
> A: "Marco Atzeri" <address@hidden>
> Cc: address@hidden
> Data: Sabato 23 maggio 2009, 08:44
> 
> On May 21, 2009, at 9:57 AM, Marco Atzeri wrote:
> 
> > 
> > Dear all,
> > on latest hg source, on cygwin-1.7, I have
> > 
> > 
> >>>>>> processing
> /pub/hg/octave_clone/scripts/polynomial/polyfit.m
> >  ***** test
> > x = [ -1196.4, -1195.2, -1194, -1192.8, -1191.6,
> -1190.4, -1189.2, -1188, \
> >       -1186.8, -1185.6,
> -1184.4, -1183.2, -1182];
> > y = [ 315571.7086, 315575.9618, 315579.4195,
> 315582.6206, 315585.4966,    \
> >       315588.3172,
> 315590.9326, 315593.5934, 315596.0455, 315598.4201, 
>   \
> >       315600.7143,
> 315602.9508, 315605.1765 ];
> > [p1, s1] = polyfit (x, y, 10);
> > [p2, s2, mu] = polyfit (x, y, 10);
> > assert (2*s2.normr < s1.normr)
> > !!!!! test failed
> > 
> > 
> > 
> > octave:5> 2*s2.normr
> > ans =  0.12583
> > octave:6>  s1.normr
> > ans =  0.11466
> > 
> > 
> > is this fault cygwin specific or do you see it
> > on other platform ?
> > 
> > 
> > For the rest I have only the already known cygwin
> faults in
> > 
> >>>>>> processing
> /pub/hg/octave_clone/src/data.cc
> > due to abs of NaN on complex.
> > 
> >>>>>> processing
> /pub/hg/octave_clone/src/syscalls.cc
> > due to fork issue.
> > 
> > Regards
> > Marco
> 
> Marco,
> 
> On the wild chance that the numerical errors are incidently
> better for you in this specific case, can you try a
> modification of the problem? Perhps ...
> 
>     [p1, s1] = polyfit (pi*x, y, 10);
>     [p2, s2, mu] = polyfit (pi*x, y, 10);
>     assert (2*s2.normr < s1.normr)
> 
> Ben
> 
Hi Ben,
in this case, the assert  is fine:

octave:5> 2*s2.normr
ans =  0.12583
octave:6> s1.normr
ans =  0.31657

Regards
Marco