[Python-Dev] Numerical robustness, IEEE etc. (original) (raw)

Nick Maclaren nmm1 at cus.cam.ac.uk
Sat Jun 24 13:15:37 CEST 2006

"Terry Reedy" <tjreedy at udel.edu> wrote:

Of interest among their C-EPs is one for adding the equivalent of our decimal module http://www.open-std.org/jtc1/sc22/wg14/www/projects#24732

IBM is mounting a major campaign to get its general decimal arithmetic standardised as THE standard form of arithmetic. There is a similar (more advanced) move in C++, and they are working on Fortran. I assume that Cobol is already on board, and there may be others.

There is nothing underhand about this - IBM is quite open about it, I believe that they are making all critical technologies freely design has been thought out and is at least half-sane - which makes it among the best 1-2% of IT technologies :-(

Personally, I think that it is overkill, because it is a MASSIVELY complex solution, and will make sense only where at least two of implementation cost, performance, power usage and CPU/memory size are not constraints. E.g. mainframes, heavyweight commercial codes etc. but definitely NOT massive parallelism, very low power computing, micro-minaturisation and so on. IEEE 754 was bad (which is why it is so often implemented only in part), but this is MUCH worse. God alone knows whether IBM will manage to move the whole of IT design - they have done it before, and have failed before (often after having got further than this).

Now, whether that makes it a good match for Python is something that is clearly fruitful grounds for debate :-)

Regards, Nick Maclaren, University of Cambridge Computing Service, New Museums Site, Pembroke Street, Cambridge CB2 3QH, England. Email: nmm1 at cam.ac.uk Tel.: +44 1223 334761 Fax: +44 1223 334679

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