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Date: | Wed, 1 Apr 2009 17:04:42 +0000 (GMT) |
From: | Marco Atzeri <marco_atzeri AT yahoo DOT it> |
Subject: | Re: complex number |
To: | cygwin AT cygwin DOT com, Greg Chicares <gchicares AT sbcglobal DOT net> |
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--- Mer 1/4/09, Greg Chicares ha scritto: > Da: Greg Chicares=20 > Oggetto: Re: complex number > A: cygwin AT cygwin DOT 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 -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
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