Stefan Hundhammer wrote:
On Saturday 28 August 2004 05:07, William A. Mahaffey III wrote:
By the by, I do do some C & (frankly) like it. Almost all new stuff I write is, in fact, in C (no good w/ C++ yet ....), unless there are definite speed requirements, whence I go to FORTRAN.
Just curious: Did you do any hard benchmarking to support that supposed performance advantage of Fortran compared to C used in a similar way - i.e. not doing any fancy stuff, just number crunching?
Any pointers, anybody?
CU
Absolutely, have posted about that in the past. I have some code that I originally ran on Convex & Cray computers, written in the late '80's, in F77 (originally), which does simple operations (dot products, matrix-vector op'ns, etc). It was motivated by linpack, but did some other operations. I have since fancied it up (with a C main routine to allocate memory & call the various F77 & C leaf routines to do the actual work & clock things, etc.), & have run it on various SGI Octanes (2 X 195, 2 X 300, 2 X 400, 2 X 600 out at MSFC in HSV, Al. USA), SGI servers (250 MHz based Origins, 600 MHz Origins), as well as a DEC Alpha based server, and numerous PCs, from 400 MHz PII up to 2400 MHz P4's, as well as AMD Athlons from 1600 MHz to 2200 MHz. F77 is 10 - 25% faster than C under commercial compilers. Commercial C compilers are 10 - 30% faster than GCC. The speedups are usually higher the more operations you do per loop. Simple assigns or copies (memset, memcpy) as equally fast under C & F77. It is only an issue if you do large numerical simulations that really do take many hours or days to complete, then any speedup is noticable.