[squeak-dev] Posits

Craig Latta craig at blackpagedigital.com
Mon Nov 14 18:37:36 UTC 2022


      Tony writes:

 > Here's a more up-to-date criticism:
 > https://hal.inria.fr/hal-01959581v2/document
 > Florent de Dinechin, Luc Forget, Jean-Michel Muller, Yohann Uguen.
 > Posits: the good, the bad and the ugly. 2018. hal-01959581v2

      Thank you! Lots of compelling future work suggested there.

 > ...since the standard posit formats have a slightly smaller range of
 > precisely-encoded contiguous integers in them, maybe regular
 > floats/doubles are better where you're doing something shady like
 > using them in place of a proper integer type (*cough cough
 > javascript*)...

      Nicolas responds:

 > Concerning languages like Javascript, please note that all integers up
 > to 2^48 are representable on Posit64 with es=2, or up to 2^52 on
 > Posit64 with es=3, if I'm not mistaken... So it does not make a great
 > difference with Float64.

      In the announcement[1] in March 2022 of the first ratified version 
of Posit standard[2]:

      "NOTE: Contrary to the original paper by Gustafson and Yonemoto, 
and to early versions of the Standard, the exponent size (eS) is always 
2 and does not vary with the precision. This greatly simplifies 
conversions between precisions and the creation of correctly-rounded 
math library functions, and in hundreds of experiments with real 
applications has shown to be a better choice. 
We thank all members of 
the Posit Working Group for their efforts."


[1] https://posithub.org/khub_doc
[2] https://posithub.org/docs/posit_standard-2.pdf

Craig Latta        :: research computer scientist ::
Black Page Digital ::     Berkeley, California    ::
663137D7940BF5C0AF ::    C1349FB2ADA32C4D5314CE   ::

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