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Date: Wed, 01 Apr 2009 15:32:32 +0000
From: Greg Chicares <gchicares AT sbcglobal DOT net>
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Subject: Re: complex number
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On 2009-04-01 14:48Z, Marco Atzeri wrote:
>
> I was trying to understand why this code
> 
> #include <iostream>
> #include <complex>
> 
> int main()
> {
>   double a = 0;
>   double b = 1. / a;
>   a += 1;
>   std::cout << std::abs (std::complex<double> (b, a)) << '\n';
>  }
> 
> produce Inf on most platform and NaN on cygwin.

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.


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