ROMS 2.2 successfully built with Gfortran

[m.hadfield]

ROMS can now be built with Gfortran. This is the free (speech and beer) Fortran compiler that is part of the Gnu Compiler Collection (GCC):

http://gcc.gnu.org/wiki/GFortran

Gfortran is distinct from G95,. another free Fortran 95 compiler based on GCC. There is a (possibly biased) description of the relationship between the Gfortran and G95 projects here:

http://gcc.gnu.org/wiki/TheOtherGCCBasedFortranCompiler

G95 has been able to build ROMS for about a year now, see

viewtopic.php?t=130&highlight=g95

however there have been bugs in Gfortran that have prevented it from compiling the code. These bugs have been fixed in recent versions of the compiler, anything later than 2005-10-15 seems to be OK.

Does Gfortran have any major advantages over G95? Probably not, though the Gfortran people are making noises about implementing OpenMP. Also in future Gfortran will be part of the GCC package, which will make installation easier. Anyway, it's another tool in the box.

G95 and Gfortran both lag somewhat behind commercial compilers in terms of performance. Here are my best times for several different compilers for the BENCHMARK1 case, 200 time steps, with 1 x 8 tiling:

P4 2.7 GHz running Windows 2000:

CVF 6.6B: 1435 s
G95: 1605
Gfortran: 1605

P4 Xeon 2.8 GHz running Linux:

Ifort 8.1: 1100 s
G95: 1410 s
Gfortran: 1570 s