Date: Mon, 4 Dec 1995 11:46:29 -0800 (GMT)
From: Orlando Andico <oandico AT gollum DOT eee DOT upd DOT edu DOT ph>
To: THutchi141 AT aol DOT com
Cc: DJGPP Mailing List <djgpp AT sun DOT soe DOT clarkson DOT edu>
Subject: Re: header file <math.h>

On Sun, 3 Dec 1995 THutchi141 AT aol DOT com wrote:

> Hi,
> 
> I am a new user of djgpp.  I have downloaded several zip files and have
> successfully
> compiled several simple C programs.  However, I have not been able to use the
> include
> file <math.h>.  A simple program, such as:
> 
> #include <stdio.h>
> #include <math.h>
> 
> main()
> {
>      printf("%d\n",sin(3.0));
> }
> 
> produces an error:
> 
> "ex2-2.c (.text + 0x24): undefined reference sin"
> 

Hi! them ``undefined reference(s)'' are actually _link_ time errors. Id 
est, the _linker_ can't find the appropriate math library! (it's libm.a)
In order to link in the math library, you have to type something like

gcc ex2-2.c -lm
             ^^^ this part says to include the math library

You don't need to worry about the ???68881.h file as that's the include 
file for the MC68881 maths coprocessor (used by Motorola cpu's, i.e. 
MC68020, that didn't have integral fpu's)

Further, the math (floating-point) routines won't work if you don't have 
a coprocessor (if you have 486DX, 487SX or higher processor, you _do_ 
have the fpu). If you don't have an fpu (like me =( ) you must add the 
ff. line to your GO32 environment variable

GO32=emu <path-to-emu-file> ... the rest of your stuff ...

The standard emulator which comes with djeoe???.zip is emu387; you can 
find this in the /bin subdirectory. If you like (although this is moot if 
you have a coprocessor...) you can use another emulator that _used_ to be 
called emu387wm (it's in the wmemu112.zip file in the SimTel distrib). I 
think it's faster than the default emulator or something...

Regards & good luck,

-------------------------------------------------------------------------------
Orly A. Andico                       Instrumentation, Control, and Robotics Lab
oandico AT gollum DOT eee DOT upd DOT edu DOT ph            Dept of Electrical & Electronics Eng'g
                                          University of the Philippines Diliman
-------------------------------------------------------------------------------