[fpc-pascal] FORTRAN from FreePascal

Mark Morgan Lloyd markMLl.fpc-pascal at telemetry.co.uk
Mon Nov 20 13:31:44 CET 2017

On 20/11/17 12:00, Schindler Karl-Michael wrote:
>> Am 20.11.2017 um 12:00 schrieb fpc-pascal-request at lists.freepascal.org:> > Date: Sun, 19 Nov 2017 11:14:50 +0000> From: Mark Morgan Lloyd <markMLl.fpc-pascal at telemetry.co.uk>> To: fpc-pascal at lists.freepascal.org> Subject: Re: [fpc-pascal] FORTRAN from FreePascal> Message-ID: <ourp3a$fub$1 at pye-srv-01.telemetry.co.uk>> Content-Type: text/plain; charset=utf-8; format=flowed> > Oh really? Well I'll let you travel back in time and argue with numerous > former colleagues who've routinely found differences between their > "fortran" (-IV, -77 or whatever) and "fast fortran" compilers which in > those days tended to be separate programs even if supplied together.
> Wasn't the problem somewhat different? There have always been "fast-math" version of some costly function. So, the point was, whether the faster routines could be used at the price of their larger numerical errors. Similarly, the choice of the optimization level of a compiler needed to be checked.
> Furthermore, the wide spread use of fortran for numerical intense simulation up to this date stands in contrast to your statement, in particular in the field called high performance computing.

Possibly. It might be that the "fast" variant of the compiler was 
actually pulling in different libraries.

However, the situation as described to me has always been in terms of 
"if you have problems don't use the 'fast' compiler" or, with more 
recent development tools "the first thing to try is turning optimisation 
off". And this advice seems to /particularly/ apply to FORTRAN.

And leaving aside for the moment a small number of specialists who I 
only know from subscription online services etc. (such things do still 
exist), I've had this in most detail from well-respected senior academic 
colleagues one of whom had been involved with the design of the 
Manchester computers back when 2K words was "more than a man can keep 
track of".

Oh, and the story about Turing suggesting using gin in the delay lines 
is inaccurate. He merely observed that gin, as an aqueous alcohol 
mixture with trace oil content, was excellent for cleaning the 
transducers before the line was filled with mercury.

But this is getting way off topic and we'll get a "moderatorial cough" 
any moment :-)

Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]

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