From bug-request at octave dot org Thu Dec 16 16:55:59 2004
Subject: Re: signbit on linux/gcc 3.2+
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Orion Poplawski <orion at cora dot nwra dot com>
Cc: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>, bug@octave.org
Date: Thu, 16 Dec 2004 17:56:58 -0500

On 16-Dec-2004, Orion Poplawski <orion at cora dot nwra dot com> wrote:

| Well, it's a GNUism:
| 
| #if _GLIBCPP_USE_C99
| #if !_GLIBCPP_USE_C99_FP_MACROS_DYNAMIC
| // These are possible macros imported from C99-land. For strict
| // conformance, remove possible C99-injected names from the global
| // namespace, and sequester them in the __gnu_cxx extension namespace.
| 
| (which is then imported into std::)
| 
| And with GNU <cmath> you are pretty much stuck with std::signbit because 
| it undefines the signbit macro.

That's fine, for systems using GCC and GNU libstdc++.  But we can't
simply use

  #include <cmath>
  using std::signbit;

on all systems, which is what I think your patch did.

jwe



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