[ale] g77 vs gfortran

[Fulton Green]

As someone who honed his programming chops with a VAX/VMS Fortran 77
compiler during college and in his first post-college workplace, I was
intrigued ...

On Tue, Feb 21, 2006 at 12:45:46AM -0500, Dow_Hurst wrote:
> I've switched to opensuse 10.0 from novell on my laptop and noticed that g77 is now gfortran.

Yep, GCC decided that it was about time to stop using a nearly thirty-
year-old spec (Fortran 77) and start using ... a ten-year-old spec
(Fortran 95).  Maybe OpenSUSE is just now updating their compilers to
the 4.x level (some of the earliest 4.0 compilers had severe compilation
and compatibility issues).

If it's not already obvious, gfortran is the GCC implementation of the
Fortran 95 spec.  There's also a separate g95 project which has forked
from GCC.

You can check out the goods here: http://gcc.gnu.org/wiki/GFortran

> A particular fortran program I've used for several years now doesn't compile with gfortran.  Is the 
> solution to download the g77 source and compile it?  I don't think there is a version of g77
> precompiled for opensuse 10.0 is there?

According to the aforementioned wiki:

http://gcc.gnu.org/wiki/GFortranG77

No one stepped up to port g77 to GCC 4.0's new front-end interface, so
it no longer enjoys official support from the GCC development team.

Depending on what the portability goals of the owners/maintainers of this
source code are, and the size of the codebase, you might want to pursue
the conversion of this code to Fortran 95.  Could it really be all that
complicated?  (Well, actually, it might be ...)

If that intrigues you and/or the original programmer, try Googling on
"differences" "Fortran 77" "Fortran 95" to get some helpful aids toward
that end.  You may also find it worthwhile to try out the g95 compiler.

If a precompiled version of g77 exists, it will be strictly from a third-
party packager of (Open)SUSE modules.  It will most likely require the
installation of the legacy GCC (3.95 or something to that effect).
Hopefully, the package installation will be GCC 4.0-aware (i.e., it won't
clobber the existing 4.0 installation or packages that it depends on).

HTH,
Fulton