Re: Numerical simulations on alphalinux: C or fortran?

[Chris Albertson <chris topdog pas1 logicon com>]

Andrei A. Dergatchev wrote:
> 
> Hi,
> 
> > Dear all,
> >
> >   I bought a alphalinux workstation to make numerical simulations.
> 
> So did I :-)
> [snip]
> 
> >   My question is will I gain in term of speed to transfer my code from
> > fortran to C?

If you use the GNU compilers the "back end" the part of the compiler
that generates the code is the same for C and FORTRAN.  I built eggs
1.1.1 from source on my ALpha and included the F77 front end in my build.
> 
> 0) Depends on your code :-)
> 
> 1) I've been dealing with large FEM calculations and what I miss a lot
> comparing to Wintel side is a tranparent debugger. Absence of
> dynamic allocation is a considerable minus for f77 vs C comparison
> if your application is a memory hog. But using g77/gdb combo it
> really gets more debugging time than what I'd prefer :-((

Get "ddd".  It is the kind of debugger you say you miss.  It is
the typical "visual" type thing where you can move a highlight
bar one line at a time through the source code while watching
variables in display windows.  Yes, it does build cleanly on Alpha
Linux.

> 
> I'd really surprised if rewriting the same from f77 to C you'll gain more
> then few % in time, but I haven't had any experience yet.

Pior to GNU F77 becomming stable I used f2c.  This is a quite robust
FORTRAN to C translator.  It comes with a script that hides the translation
phase.  Makes you think you are running a real F77 compiler.  One could
use f2c and your current copy of eggs.  Worked for me on about 100,000
lines of FORTRAN.
> 
> [snip]
> 
> >
> > Thamks in advance,
> >
> > Lorenzo Bernardi
> 
> Regards,
> 
> Andrei
> 
> --
> To unsubscribe: send e-mail to axp-list-request@redhat.com with
> 'unsubscribe' as the subject.  Do not send it to axp-list@redhat.com

-- 
--Chris Albertson

  chris@topdog.logicon.com                Voice:  626-351-0089  X127
  Logicon RDA, Pasadena California          Fax:  626-351-0699