How do I install a Fortran compiler using cygwin on a Windows 7 32-bit machine?
cygwin packages gfortran, see the results here (for x86, that is 32-bit) https://cygwin.com/cgi-bin2/package-grep.cgi?grep=gfortran&arch=x86
I suggest that you pick that most recent, gcc-fortran-6.3.0-1. You can install it as any other cygwin package.