[vox-tech] math.h advice?

Jeff Newmiller vox-tech@lists.lugod.org
Mon, 8 Jul 2002 19:35:59 -0700 (PDT)


On Mon, 8 Jul 2002, Peter Jay Salzman wrote:

> yes.
> 
> #including a file doesn't bring in code.  it brings in things like
> prototypes, global variables, includes, defines, etc.
              ^^^^^^^^^^^^^^^^

... to be precise, the declarations of global variables.  The global
variables themselves are also in the library, brought in with the "-lm".

   extern int myglobal;   /* declaration... exists somewhere.... */
   int myglobal;          /* allocates space for the variable,
                             normally only used in a .c file  */

> 
> everything except the actual code.
> 
> -lm brings in the code.
> 
> pete
> 
> begin Alexandra Thorn <amthorn@ucdavis.edu> 
> > 
> > Mike,
> > 
> > Thanks for your suggestion.  Now just to confirm that I understand you,
> > are you saying that I just just add the option -lm at the end of the
> > compile command line line?
> > 
> > Thanks again,
> > Alex
> > 
> > On Mon, 8 Jul 2002 msimons@moria.simons-clan.com wrote:
> > 
> > >   Add "-lm" to your gcc link line... that asks gcc to link in the math
> > > library.  "-l" says link in the following library "m" is the name of the
> > > math library.
> > >
> > >   So "gcc -o run_me infile.c -lm" should produce a run_me...
> > >
> > >   If not please paste the error messages you see.
> > >
> > >     Good Luck,
> > >       Mike
> > > _______________________________________________
> > 
> > _______________________________________________
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> > vox-tech@lists.lugod.org
> > http://lists.lugod.org/mailman/listinfo/vox-tech
> 
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