std::arg() bug : not repetitive ?

[Marco Atzeri]

--- Gio 3/9/09, Dave Korn  ha scritto:

> Da: Dave Korn 
> Oggetto: Re: std::arg() bug : not repetitive ?
> A: cygwin-apps cygwin.com
> Data: Giovedì 3 settembre 2009, 06:07
> Brian Ford wrote:
> > On Wed, 2 Sep 2009, Marco Atzeri wrote:
> > 
> >> I have no clue if -march=pentium4 is acceptable
> for AMD cpu's.
> > 
> > FWIW, we have been using -march=pentium4 -mfpmath=sse
> successfully in a
> > very large software project since November 2003
> without incident.  We have
> > run on AMD Opterons and a variety of Intel processors
> without issue
> > (given that they were at least Pentium 4's, of
> course).
> > 
> 
> In http://lkml.indiana.edu/hypermail/linux/kernel/0904.2/00818.html
> it is
> argued that:
> 
> > Nvidia started requiring SSE in their binary drivers,
> but have since
> > backed out that requirement, so it is possible to make
> people realize
> > their code has unreasonable requirements.
> 
>   If we turn on SSE in the distro, we block anyone
> using Pentium2 or early
> (pre-XP) Athlon CPUs from using Cygwin.  I think that
> might be a step too far.
>  In the place where I was working until only last November,
> we had a ton of
> old P2 boxes around the place, doing useful jobs, and they
> all had Cygwin on
> them.  It would have crippled us if we suddenly had to
> upgrade them all one day.
> 
>   OTOH maybe we could hack up a software SSE emulation
> for those users...
> 
>     cheers,
>       DaveK
> 
Hi Dave,

I am trying to convince octave developers to add 
an additional z1!=z2 before the comparison of 
abs(z1) < abs(z2) and 
arg(z1) < arg(z2).

This should resolve the truncation problem of arg and abs
when comparing two equal complex numbers.

Eventually I will add that only for cygwin,
it seems simpler than non standard arch settings 
for the package.

Thanks 
Marco