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Date:	Wed, 1 Apr 2009 14:47:55 -0400
Message-ID:	<f60fe000904011147q55181211o6230d1deb626c5c7@mail.gmail.com>
Subject:	Fwd: complex number
From:	"Mark J. Reed" <markjreed AT gmail DOT com>
To:	cygwin AT cygwin DOT com
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On Wed, Apr 1, 2009 at 1:30 PM, Corinna Vinschen wrote:
>
> > > That's the result of the newlib function which is defined
> > > as
> > >
> > > =C2=A0 double
> > > =C2=A0 cabs(z)
> > > =C2=A0 struct complex z;
> > > =C2=A0 {
> > > =C2=A0 =C2=A0 return hypot(z.x, z.y);
> > > =C2=A0 }
> > >

That's from the newlib source code, I assume? While the function
cabs() exists inside newlib, and is declared as an extern in math.h,
it's not documented, nor is there a prototype for it or a declaration
of "struct complex" that I can find anywhere in the installed headers
(just the "complex" typedef in the gcc headers, whose structure
doesn't match the above).=C2=A0 l Yet somehow the compiler is doing some
sort of typechecking anyway and rejecting everything I try to pass as
a parameter, so I can't validate the return value of cabs.

Did you determine that the C++ std::complex::abs() method winds up
calling cabs() eventually, or was that a guess?=C2=A0 It's strange, because
calling hypot(a, b) directly yields the correct result.

--
Mark J. Reed <markjreed AT gmail DOT com>

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