There is a problem with using sqrt() and other math functions on SNOWBALL.
Just including <math.h> is not enough. If you encounter this, try using "-lm"
on the command, linking the math library. Here's an example:

[myacct123@gsuad.gsu.edu@snowball]$ gcc hmwk4_myacct123.c 
/tmp/cc9RiswK.o: In function `getDistance':
hmwk4_jhill144.c:(.text+0x26d): undefined reference to `pow'
hmwk4_jhill144.c:(.text+0x297): undefined reference to `pow'
hmwk4_jhill144.c:(.text+0x2a1): undefined reference to `sqrt'
collect2: error: ld returned 1 exit status
[myacct123@gsuad.gsu.edu@snowball]$ gcc hmwk4_myacct123.c -lm

Notice that the fix is not changing the C program, but changing 
the command to compile/link it.
For more detail, here's a good place to start:
https://stackoverflow.com/questions/5248919/undefined-reference-to-sqrt-or-other-mathematical-functions