From bug-request at octave dot org Thu Dec 16 21:35:50 2004
Subject: Re: signbit on linux/gcc 3.2+b
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Orion Poplawski <orion at cora dot nwra dot com>
Cc: bug at octave dot org
Date: Thu, 16 Dec 2004 22:36:55 -0500

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

| Does the following work on the sun?
| 
|    #include <cmath>
|    #include <iostream>
|    int
|    main (void)
|    {
|      std::cerr << signbit (-1.0) << std::endl;
| 
|      return 0;
|    }

I don't see evidence of a signbit function or macro on the Sun systems
that I have access to.  They do have copysign, so

|   #define lo_ieee_signbit(x) (x < 0 || copysign (1.0, x) < 0)

should be an option.

| Just for fun, see 
| http://osl.iu.edu/~tveldhui/papers/techniques/techniques01.html

I think some of these points are a bit pessimistic these days (the
report is more than 4 years old now).  I don't think current compilers
are so bad.

jwe



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