Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!cmcl2!lanl!jlg From: jlg@lanl.gov (Jim Giles) Newsgroups: comp.lang.fortran Subject: Re: Fortran versus C for numerical anal Message-ID: <3963@lanl.gov> Date: 21 Sep 88 20:03:52 GMT References: <1475@valhalla.ee.rochester.edu> Organization: Los Alamos National Laboratory Lines: 22 From article <1475@valhalla.ee.rochester.edu>, by davis@galaxy.ee.rochester.edu (Al Davis): > Here is a challenge: write a portable program that does LU decomposition of > a matrix of arbitrary size, in Fortran. I believe it can't be done, in a > straightforward way. (Read the input, do it, write the result) > Someone please prove me wrong. We have a Monte-Carlo particle code that uses dynamic memory. It is entirely written in standard Fortran except for the two routines that actually allocate and free the dynamic memory. The code has been ported to IBM, DEC, CDC, and Cray mainframes as well as several other machines. The portability problems are limited to differences in file naming conventions on the various systems and to numerical differences in the hardware. These problems would effect porting a code written in _any_ language. Please note that the C dynamic memory routines _also_ can't be written entirely in C. At some point a call to the system to change the program's field length (or other memory mapping strategy) must be used. On any given system, brk() is usually written in assembly or at least has some in-line assembly code. J. Giles Los Alamos