gfortran build of FAST

I’m attempting to compile, link, and build a FAST executable for a 32-bit Windows XP platform with the open-source/free FORTRAN compiler-- “gfortran.”

At present, I find that trying to compile the NWTC library source module “SysSubs” isn’t working because the Windows source files (SysVF.f90, SysIVF.f90 or SysCVF.f90) have USE statements looking for the compatibility/portability modules “IFPORT” or “DFPORT.”

Googling “gfortran” with IFPORT and DFPORT wasn’t too helpful-- other than indicating that users of gfortran have run into this problem when attempting to compile CVF or IVF or ifort code w/ gfortran.

Any FAST users out there using gfortran? Any ideas on a work-around?

Toby Wehrhan

FAST Users,

FYI, here is what Steven Bosscher ( at the GNU compiler group wrote back to me regarding IFPORT and DFPORT…

DFPORT is the DEC Fortran portability library. Intel’s Fortran
compiler has historic links to the DEC compiler, and apparently they
still have this library, just renamed Intel Fortran portability
library i.e. IFPORT. Intel appears to discourage the use of
DFPORT/IFPORT for new code
( … ifport.htm),
but I couldn’t find a porting guide or anything.

What the library provides is mostly covered with intrinsics in
gfortran. Things may just work if you remove the USE statements. You
should try that first. If you find that there are compiler errors due
to missing functions/subroutines, you could report those here and get
case-by-case help (either with suggestions for replacement with
standard functions, or implementations, etc.).

See also for how
you can use SYSTEM to replace some functionality of DFPORT.


Hi Steven,
glad to see you like the “free way” of compilers…you can find on this forum a post about how I compiled FAST with G95 … I wrote a SysG95.f90 (and a ModG95.f90 that was for previous version of fast) for that, and now I think it is distributed in the package or available from the net.
I see that now in the NWTC library there is a SysGnu.f90 that is for Gnu Fortran on Linux… give it a try, maybe could help… I’m really curious


Oh…btw with G95 I experienced a huge lack in speed with respect to Compaq or Intel compilers, even with hard optimization. I was investigating also Silverfrost FTN95 another free compiler…



Glad to find another open/“free” compiler enthusiast. At the moment, I’ve got to move very fast on getting a FAST simulation to work, so I’ve ponied-up the ~$700 to Intel for IVF. I’ll get back to trying to trying out gfortran later. By the wa,y it was Scott Larwood who suggested gfortran, as he had heard (perhaps from you) about g95 being slow. Actually, now that I think about it, its likely from his direct experience, as he used g95 to compile his CurveFast code.

In any case I’ll keep you posted on my progress.



Tobias Wehrhan
Oak Engineering, LLC
718 Oak Ave.
Davis, CA 95616