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fluberman

macrumors newbie
Original poster
Nov 23, 2004
2
0
I have been a pc user all the time, although I spend most of time running my PC under linux and now I'm considering to switch. I am also doing some programming using fortran 95 (intel fortran for linux, which is free). As far as I know, under mac os x I can run g95 or gfortran but they are still under heavy development. Does somebody here have any experience in running g95/gfortran and how about it's performance compared to a commercial compiler such as Absoft fortran ? I do really want to swich, but this issue is important to me. Thanks.
 

bousozoku

Moderator emeritus
Jun 25, 2002
16,120
2,397
Lard
Absoft recently started selling IBM's XLF compiler, apparently, instead of their own. It's AltiVec-aware so it should provide good performance and it's G5/PPC970-aware so it can handle larger memory spaces.
 

jeremy.king

macrumors 603
Jul 23, 2002
5,479
1
Holly Springs, NC
gwuMACaddict said:
still used quite frequently in finite element analysis and computational fluids

:confused: what the heck is that?

Out of curiousity, what makes one language better than another in the field of computational fluids?

I got to go gooooooogling now. :)
 

visor

macrumors 6502
May 13, 2003
341
0
in bed
kingjr3 said:
:confused: what the heck is that?

Out of curiousity, what makes one language better than another in the field of computational fluids?

Usually - the existing codebase. Somtimes better Compiler performance, however, if someone asks if there are compilers available - it's the existing codebase ,)
 

mwpeters8182

macrumors 6502
Apr 16, 2003
411
0
Boston, MA
I took a class in Numerical methods during last semester (1st semester of grad school). We programmed exclusively in fortran, and I belive my prof. said g95 would work ok, though we used absoft's compiler.

MP
 

mkrishnan

Moderator emeritus
Jan 9, 2004
29,776
15
Grand Rapids, MI, USA
kingjr3 said:
:confused: what the heck is that?

Out of curiousity, what makes one language better than another in the field of computational fluids?

I got to go gooooooogling now. :)

The usual argument is that Fortran has the highest efficiency in compiling to machine code...that is, the ratio of the theoretical number of floating point and integer ops that the actual scientific problem takes, to the number of ops that the *computer program* takes is very favorable. So it's good for techniques that are essentially brute force, in the sense that they model a complex system by modelling relatively simple equations (such as basic fluid equations or Maxwell's electromagnetic equations) on a really fine mesh and/or lots of elements.

We used to use Fortran for modelling discrete particles (electrons and ions) in relativistic (but not QED) EM fields in plasma physics....

Oooh, btw, is there stuff you can't do in G77?
 

mwpeters8182

macrumors 6502
Apr 16, 2003
411
0
Boston, MA
My guess is that if he had been programming in F90/95, G77 wouldn't work, as it adheres to the old (F77) standard IIRC, which requires strict formatting and all - F90 is MUCH easier to code in than F77. I'd give G95 and gfortran a try -- they're available here :

http://hpc.sourceforge.net/

MP
 
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