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From: mcdonald@uxe.cso.uiuc.edu
Newsgroups: comp.lang.fortran
Subject: Re: FORTRAN Horror (speed of FORTRA
Message-ID: <50500044@uxe.cso.uiuc.edu>
Date: 2 Apr 88 15:09:00 GMT
References: <1508@vaxb.calgary.UUCP>
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Nf-ID: #R:vaxb.calgary.UUCP:1508:uxe.cso.uiuc.edu:50500044:000:2427
Nf-From: uxe.cso.uiuc.edu!mcdonald    Apr  2 09:09:00 1988



>However... I can well beleive that most FORTRAN programs ran slower
>than they would have if written in Pascal. Most FORTRAN programs are
>not dominated by numeric computations. The FORTRAN IO system was
>abysmally slow, due to the need to interpret formats at run time, plus
>general brain damage. I find it rather amusing how scientists and
>engineers insist of using FORTRAN for "numeric" applications which are
>90% IO, data conversion, and control, applications for which it is
>wholely inappropriate, *especially* if you are not a professional 
>programmer.

>   Radford Neal

I find this comment most curious. Disregarding Pascal for the moment,
I've surveyed the Fortran programs around here (the University of
Illinois Chemistry Department) twice in 15 years, and find that only
a small amount of time is spent doing IO. Most, by far, is spent in either
actual computation, or in a wait loop looking for user input. Only 
one group uses a substantial amount of IO (while diagonalizing
100000x100000 sparse matrices) and believe me, they make SURE that it is 
as efficient as possible! At the time of my first survey, 1975, I
was the largest computer user; my main program output about 10 kbyte
of data every 30 minutes of computing (on the Illiac IV).  Today I
do a lot of O, very little I, with most of the O going to graphics
devices which are totally language-independent- everything in their 
drivers is in assembler. Actually the Fortran IO system is more efficient
than most, as it allows direct block IO explicitly, if you use it right.
In real scientific programs, no one uses formatted IO for intermediate
results.  I do agree that the default behaviour of the Fortran formatted
IO system is unsatisfactory for interactive use --- that is its biggest
problem and the reason that, for instance, C is becoming more popular.

As to Pascal--- since I have never seen anyone write a scientific program
in it, I can't comment directly, but looking at the standard Pascal
definition, I can't see that it would be any better than Fortran:
it lacks a LOT that Fortran has, so much, in fact, that it is really a toy.
The only real alternative to Fortran is C, which has its own problems
for scientific use: no Complex type, and problems with convenience 
handling multidimensional arrays; it's also harder to write a really
good optimizer for C, due to aliasing (see the discussions in comp.lang.c).

Doug McDonald