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Why do I use Fortran90, vim and Linux etc.

Often people ask me why do I use Fortran90, vim and Linux when there are so many other alternatives about there. So this is my chance to rant and rave back at them!

Why Fortran90 and not C/C++: There are various reasons for this one, most of the software I have to support was originally written in F77 is a big reason. I also believe that F77 is faster for numerical work than C/C++ and the F90 compilers will catch up to the F77 ones soon. I don't really lack anything I need from F90 you get with C/C++, for instance for serious graphics programming I would only really consider OpenGL and GLUT and both of these have Fortran interfaces. If you can't afford OpenGL, Mesa is a free OpenGL clone that runs on nearly all UNIX X-windows machines and works with GLUT. Fortran compilers are widespread, for instance when the first Cray T3D was delivered to the U.K. the only parallel compiler available was a Fortran one, the C compiler didn't come until 4-6 months later. Fortran90 also allows the use of dynamic memory allocation for an example of a program using this look over here, this program was written by me to calculate the coloumbs interaction between atoms in a solution. Originally it was for a small system but then it grew until I decided to look at the dynamic memory allocation. It is slightly slower now but can handle alot more. With the release by Intel of their own C/C++/F90 compilers for linux then there is no problem now in using F90 under Linux. Why vim and not emacs: I manage the computers for our group and when they arrive you most certainly do not find emacs pre-loaded, this means to actually set the machine up the editor available is vi (not vim I know). So I use vi, however I do realise that vi is not as user-friendly as emacs can be so after I get the machines running I install vim which is an improved version of vi and does everything I want of an editor. For one thing when I want to edit a file typing vim -g file.dat I get the file opened on my desktop in an X11 window in under 1 second, I have access to all the goodies I could want like split screens etc. If I type emacs file.dat about 8 seconds later it's ready to go - far too long for me to wait.

Why Linux and not WinXX: This is an easy one actually, at work all our serious workstations are some variety of UNIX (AIX, IRIX), if I use a mini-computer it has UNIX. Even if I use a parallel machine e.g. SP2 it's UNIX. Even Cray's like the T90 and T3E are UNIX. It therefore makes sense for me to use UNIX on the PC's aside from the compatibilty issues look at what you get free with Linux:

For production code on the Linux cluster here I use the PGI compiler suite because its code is so much faster (but at a price!) than the GNU ones. I've also used the Intel Performance compilers and was impressed with them as well. If you want to know more about the various versions of fortran for Linux then look here as this chap seems to know more than anyone else on the subject.

My personal machines

Well some people have asked me what after all this do I have on my desk. Well the current machine on my desk at work is a very nice White Box, AMD Duron 1.3 with a fully integrated Asus A7N266-VM Nvidia main board. Its got 768Mb of DDR ram and two disks in it running Linux software raid-1. This box runs my stuff quite happily. We have more or less unlimited access and time on our own Beowulf so I do most of my number crunching on those batch machines and the analysis/prep stuff on the White Box. There is a plan at the moment to upgrade the cluster and to use some of the 2000+ cpus to upgrade the desktop machines, also to push the memory to 1Gb. For more details on this and my machines at home look here.

Last update: Tue Mar 23 22:24:04 CST 2004 Comments to: jon _at_ sinica.edu.tw
These pages were created using vim -a very much vi-improved.
Opinions on these pages are generally not Academia Sinica's.