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Date: Wed, 1 Apr 2009 17:04:42 +0000 (GMT)
From: Marco Atzeri <marco_atzeri@yahoo.it>
Subject: Re: complex number
To: cygwin@cygwin.com, Greg Chicares <gchicares@sbcglobal.net>
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--- Mer 1/4/09, Greg Chicares  ha scritto:

> Da: Greg Chicares=20
> Oggetto: Re: complex number
> A: cygwin@cygwin.com
> Data: Mercoled=EC 1 Aprile 2009, 17:32
> On 2009-04-01 14:48Z, Marco Atzeri
> wrote:
> >
> > I was trying to understand why this code
> >=20
> > #include <iostream>
> > #include <complex>
> >=20
> > int main()
> > {
> >=A0=A0=A0double a =3D 0;
> >=A0=A0=A0double b =3D 1. / a;
> >=A0=A0=A0a +=3D 1;
> >=A0=A0=A0std::cout << std::abs
> (std::complex<double> (b, a)) << '\n';
> >=A0 }
> >=20
> > produce Inf on most platform and NaN on cygwin.
>=20
> As I read C++2003 26.2/3, this use of std::abs has
> undefined
> behavior, so NaN would be conforming even though Inf would
> be less surprising.
>=20
>=20

you could be right but, I expect that gcc-4.3.2 work=20
in similar way in linux and cygwin, so a call to cabs.
In newlib cabs is wrapper for hypot and=20
hypot (0, Inf) gives Inf=20

Regards
Marco





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