Re: How to use trigonometric functions in Swarm?

[Gary Polhill]

Perrone Alessandro wrote:
> 
> Hi
> I have to use in my simulation some trigonometric functions.
> I imported the right header, but when I call the sin(x) function, an
> error occur!!
> I am using Linux on my Imac, with Swarm 2.1.1
> Here it is the result with a simple program:
> 
> ------
> address@hidden apps]# gcc alex.c -o alex
> /tmp/ccHDfVDm.o: In function `main':
> /tmp/ccHDfVDm.o(.text+0x20): undefined reference to `sin'
> /tmp/ccHDfVDm.o(.text+0x20): relocation truncated to fit: R_PPC_REL24 sin
> collect2: ld returned 1 exit status
> address@hidden apps]# more alex.c
> #include <stdio.h>
> #include <math.h>
> 
> int main () {
>     float a;
>     a=(float) sin((double) 1.0);
>     printf("%f\n",a);
> return 0;
> }
> address@hidden apps]# gcc -I/usr/include alex.c -o alex
> /tmp/cck3PTSF.o: In function `main':
> /tmp/cck3PTSF.o(.text+0x20): undefined reference to `sin'
> /tmp/cck3PTSF.o(.text+0x20): relocation truncated to fit: R_PPC_REL24 sin
> collect2: ld returned 1 exit status
> address@hidden apps]#

This is a linker error -- you need a -lm to tell it to link in the
maths library (i.e. in the compile command above, do

gcc -I/usr/include alex.c -o alex -lm

If your libm.a is not in a standard location you will need a
-L/path/to/math/library in there as well (where /path/to/math/library is
replaced by the appropriate directory path).

You should not have this problem when compiling with swarm -- I'm fairly
sure it already links in the maths library -- this may be different in
Swarm 2.x -- I'm still on 1.4.1 :-(   If not, you could add an APPLIBS=-lm
line in your makefile (or if you already have an APPLIBS line, add -lm to the
end of that -- again, this could be different in versions of Swarm higher
than 1.4.1....

Gary


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