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*To*: schlie@xxxxxxxxxxx*Subject*: Re: Nitpick with FLOOR etc.*From*: Aubrey Jaffer <agj@xxxxxxxxxxxx>*Date*: Sat, 16 Jul 2005 13:43:30 -0400 (EDT)*Cc*: sperber@xxxxxxxxxxxxxxxxxxxxxxxxxxx, srfi-70@xxxxxxxxxxxxxxxxx*Delivered-to*: srfi-70@xxxxxxxxxxxxxxxxx*In-reply-to*: <BEFE3FB8.AD89%schlie@xxxxxxxxxxx> (message from Paul Schlie on Sat, 16 Jul 2005 04:38:16 -0400)*References*: <BEFE3FB8.AD89%schlie@xxxxxxxxxxx>

| Date: Sat, 16 Jul 2005 04:38:16 -0400 | From: Paul Schlie <schlie@xxxxxxxxxxx> | | > If the stipulation that inexacts args produce inexacts results takes | > priority over finding the closest integer, then only inexact integers | > are eligible. For an implementation having IEEE-754 64.bit flonum | > inexacts: | > | > procedure #i-/0 #i+/0 | > ========= ===== ===== | > | > floor error 179.76931348623157e306 | > | > ceiling -179.76931348623157e306 error | > | > truncate -179.76931348623157e306 179.76931348623157e306 | > | > round -179.76931348623157e306 179.76931348623157e306 | | - are you proposing that a run-time error must be signaled; or more | reasonably only that it may, and/or alternatively return -1/0 +1/0 ? | [which I tend to view as being equivalent to #i-/0, #i+/0] My chart proposed no change to R5RS. These large magnitude numbers are simply those IEEE-754 numbers satisfying the R5RS descriptions of these procedures. Oops! -- (floor #i-/0) and (ceiling #i+/0) are not automatically allowed to be errors by R5RS because these procedures are expected to return inexacts for inexact arguments. I will add to the description: For an inexact argument x, it is an error if there is no inexact integer which satisfies the procedure description; for example calling `(floor -/0.)' or `(ceiling +/0.)' in an implementation having IEEE-754 64.bit flonum inexacts. | - what about -0/1, +0/1 ? All four functions return zero for an argument of zero. There are no infinitesimals in SRFI-70. | - should (= (floor x) (/ (ceiling (/ x))) [or reasonable approximation] ? (let ((x -5)) (= (floor x) (/ (ceiling (/ x))))) ==> #f

**References**:**Re: Nitpick with FLOOR etc.***From:*Paul Schlie

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