Bash shell, 126 - 169 - 156 - 140 characters
Should work in any semi-modern Bash I think (tested with GNU bash, 3.2.48(1) x86_64-apple-build).
Handles division by zero (Nan case).
All suggestions and comments welcome!
for a in $@;do
s+={`echo $@|tr ' ' ,`}{+,-,*,/};done
for i in `eval echo ${s::${#s}-9}`;do
[[ $i == */0* ]]&&y=Nan||y=$[$i];echo $i=$y;done
Supply parameters via command line:
./combinate.sh 5 0 12
