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*To*: andre@xxxxxxxxxxxxxxxxx*Subject*: Re: Arithmetic issues*From*: Aubrey Jaffer <agj@xxxxxxxxxxxx>*Date*: Wed, 19 Oct 2005 10:14:51 -0400 (EDT)*Cc*: srfi-77@xxxxxxxxxxxxxxxxx*Delivered-to*: srfi-77@xxxxxxxxxxxxxxxxx*In-reply-to*: <Pine.GSO.4.60.0510190735130.4837@xxxxxxxxxxxxxxxxx> (message from Andre van Tonder on Wed, 19 Oct 2005 07:47:30 -0400 (EDT))*References*: <y9lzmp775oz.fsf@xxxxxxxxxxxxxxxxxxxxxxxxxxx> <Pine.LNX.4.58.0510181143440.2071@xxxxxxxxxxxxxx> <Pine.LNX.4.58.0510181913570.8761@xxxxxxxxxxxxxx> <Pine.GSO.4.60.0510190735130.4837@xxxxxxxxxxxxxxxxx>

| Date: Wed, 19 Oct 2005 07:47:30 -0400 (EDT) | From: Andre van Tonder <andre@xxxxxxxxxxxxxxxxx> | | On Tue, 18 Oct 2005, bear wrote: | | >> The bitwise operations operate on exact integers only. Should | >> they live in the section on exact arithmetic? Should they carry | >> ex prefixes? Or should they be extended to work on inexact | >> integers as well? | > | > I would say that having them operate on exact integers in the | > first place is questionable; These are operations on bit vectors, | > not operations on numbers, and their semantics require | > information (the vector length) which is not expressed by the | > numbers. To say that they are defined on numbers is to confuse | > the number with a particular representation. | | I share the discomfort with the bitwise operations. As far as I | can tell, the SRFI does not portably specify the value of | (BITWISE-NOT 42). SRFI-60 "Integers as Bits" defines the bitwise operations for all integers. And the reference implementation is written portably in R5RS Scheme. (BITWISE-NOT 42) ==> -43 | Are these operations truly going to be useful for portable | programs? Yes. In SLIB they are used for Byte/Number Conversions, Cyclic Checksum, Fast Fourier Transform, Space-Filling Curves, Portable Image Files, Random Numbers, and integer-sqrt.

**Follow-Ups**:**Re: Arithmetic issues***From:*Andre van Tonder

**References**:**Arithmetic issues***From:*Michael Sperber

**Re: Arithmetic issues***From:*bear

**Re: Arithmetic issues***From:*bear

**Re: Arithmetic issues***From:*Andre van Tonder

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