[Rd] Standalone Mathlib, C++ and ISNAN()
John W. Eaton
jwe at bevo.che.wisc.edu
Thu Jan 6 05:31:25 CET 2005
On 6-Jan-2005, Bill Northcott <w.northcott at unsw.edu.au> wrote:
| On 06/01/2005, at 9:12 AM, Thomas Lumley wrote:
| >> It was suggested by one of the gcc people, but I could find no
| >> documentation about it. The ISO C++ docs do not include isnan as a
| >> symbol provided by cmath within the std namespace. I looked at the
| >> gcc source code and could see no reason why it should work.
| > Hmm. What *are* C++ programmers supposed to use to test for NaN,
| > then? It might well not be anything in the ISO standard, just as it
| > isn't in C89, but surely there is some prescribed way to do it.
| I asked the same question. So far I got no response.
What I finally decided to do for Octave was to use a C language
autoconf test for isnan, then provide a function declared "extern C"
that is a wrapper around the C isnan function (if it exists). I also
use this method for other functions that may be easier to call from C
than directly from C++.
www.octave.org | www.che.wisc.edu/~jwe | Peace would shock and awe me.
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