I'm trying to use the sqrt() function in Linux with GCC v3.3.6,

compiling with this command:

$ gcc sourcefile.c

I get this error:

In function 'main': undefined reference to 'sqrt'

collect2: ld returned 1 exit status

Here is my source code:

#include <stdio.h>

#include <math.h>

main()

{

double num, sq_double;

scanf("%d", &num);

sq_double = sqrt(num);

}

What am I doing wrong? Is there something special I need to do to use

the math.h functions?