signbit

[Ian Lance Taylor]

Koh-ichiro YOSHIURA <kyoshi@net.nagasaki-u.ac.jp> writes:

> I am a biology researcher working in University.
> I am compiling one calculation program.  I had a trouble for compiling on
> MacOSX (10.3.9) with gcc 3.3.
> 
> Error massage is following.
> "BFunction.cc:615: error: `signbit' undeclared (first use this function)"
> 
> How can I overcome this?   I cannot compile because gcc 3.3 is not included
> signbit function?

This is a question about the C++ language.  It is not a question about
gcc.  So this is the wrong mailing list.

First, gcc is a compiler, not a library.  The signbit function is
provided by your system library.

Second, before you can call signbit it must be declared.  On GNU/Linux
systems, it is declared in math.h, so you must #include <cmath> before
calling signbit.

(I don't have access to a MacOS X system myself.)

Ian