math.h - exp

[Claudio Bley]

On Thu, Sep 04, 2003 at 05:53:54AM +0200, didier wrote:
> I have installed gcc 3.3.1 on a PC-linux system, with bootstrap by gcc 
> 2.96. Every thing was right. But in a test program, the calll of the 
> "exp" function generated an error message " undefined reference to 
> 'exp', thought I include the file <math.h>. What is the reason ?

Including a header file usually is not enough as it usually only
contains function declarations / prototypes. You need to link with the
math library `libm' which provides the compiled code for the various
math functions such as `exp':

gcc prog.c -lm

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