Changes between Version 24 and Version 25 of NumericTower
 Timestamp:
 10/17/13 12:59:58 (4 years ago)
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NumericTower
v24 v25 3 3 This is an analysis of the R5RS provision that the full numeric tower may be subsetted. Four boolean feature settings characterize different kinds of numeric towers: `exactnesspreserving`, `ratios`, `inexact`, and `complex`. These refer respectively to the closure of exact numbers under rational operations (except `/`), exact noninteger values, inexact rationals, and nonreal numbers. 4 4 5 There are therefore 16 possible numeric towers. Nineof them are known to have implementations, as shown below. I write `+` if a feature is present and `` if it is absent, and give a general description of the resulting tower and some Scheme implementations that provide it.5 There are therefore 16 possible numeric towers. 8 of them are known to have implementations, as shown below. I write `+` if a feature is present and `` if it is absent, and give a general description of the resulting tower and some Scheme implementations that provide it. 6 6 7 7 `exactnesspreserving``ratios``inexact``complex`DescriptionImplementations 8 8 A "toy" tower with bounded exact integers only (possibly appropriate where no numerical work will be done)!SigScheme* 9 +Fixnums and flonums (all arithmetic runs in essentially constant time)Plain Chicken, Shoe*, !TinyScheme*, RScheme, BDC*, XLisp*, Schemik*, VX, SXM*, Inlab, Sixx, Sizzle (also Elisp*, C*) 10 ++Fixnums, flonums, and inexact complex numbers (all arithmetic runs in essentially constant time)Stalin 9 +Fixnums and flonums (all arithmetic runs in essentially constant time)Plain Chicken, Shoe*, !TinyScheme*, RScheme, BDC*, XLisp*, Schemik*, VX, SXM*, Inlab, Sixx, Sizzle, Stalin (also Elisp*, C*) 11 10 +++Limitedrange exact and inexact numbersS7, Wraith 12 11 ++Exact integers and inexact real numbers (a good allround compromise)Bigloo, Scheme 9, Elk (also ISLisp)