[Python-Dev] Floor division (original) (raw)

Nick Maclaren nmm1 at cus.cam.ac.uk
Thu Jan 25 11:24:38 CET 2007

Armin Rigo <arigo at tunes.org> wrote:

Thanks for the clarification. Yes, it makes sense that mod, divmod and floordiv on float and decimal would eventually follow the same path as for complex (where they make even less sense and already raise a DeprecationWarning).

Yes. Though them not doing so would also make sense. The difference is that they make no mathematical sense for complex, but the problems with float are caused by floating-point (and do not occur for the mathematical reals).

There is an argument for saying that divmod should return a long quotient and a float remainder, which is what C99 has specified for remquo (except that it requires only the last 3 bits of the quotient for reasons that completely baffle me). Linux misimplemented that the last time I looked.

Personally, I think that it is bonkers, as it is fiendishly expensive compared to its usefulness - especially with Decimal! But it isn't obviously WRONG.

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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