Using mex to compile fortran code

I have Matlab R2012b (8.0.0.783) 64bit (maci64) installed in a Mac OS X (10.8.8) - Snow leopard. For compiling FORTRAN I have installed the GNU gfortran 4.3.4 which according to http://www.mathworks.com/support/compilers/R2012b/maci64.html is supported by my matlab's version.

I have coded the mexopt.sh file in order to allow matlab to find the gfortran as follows:

            FC='/usr/local/bin/gfortran'
            FFLAGS='-fexceptions -m64 -fbackslash'
            FC_LIBDIR='/usr/local/lib/'
            FC_LIBDIR2='/usr/local/lib/gcc/x86_64-apple-darwin/4.3.4/'
            FLIBS="\$MLIBS-L\$FC_LIBDIR"
            FOPTIMFLAGS='-O5 -funroll-loops -ftree-vectorize'
            LDDEBUGFLAGS='-g'

Without this workaround I got the message gfortran: unknown command, although through the terminal I was able to run gfortran.

Meanwhile, when trying to compile the example timestwo.F (from matlab examples) by making

mex timestwo.F

I get the following error: -o: command not found which I think is related to the linking process since by just compiling

mex -c timestwo.F

Can someone who has more experience and knowledge help me out? I would be grateful.

Thanks in advance.

Ricardo