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fix docs for `round' et al.

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They don't return integers for +inf.0, -inf.0, and +nan.0.
This commit is contained in:
Matthew Flatt 2011-09-29 16:52:00 -06:00
parent 99fe14b080
commit a0805f9b18
1 changed files with 18 additions and 13 deletions
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31
collects/scribblings/reference/numbers.scrbl
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@ -378,35 +378,40 @@ Returns the @as-index{least common multiple} (a non-negative number)
@mz-examples[(lcm 10) (lcm 3 4.0)]}
@defproc[(round [x real?]) integer?]{
@defproc[(round [x real?]) (or/c integer? +inf.0 -inf.0 +nan.0)]{
Returns the integer closest to @racket[x], resolving ties in favor of
an even number.
an even number, but @racket[+inf.0], @racket[-inf.0], and @racket[+nan.0]
round to themselves.
@mz-examples[(round 17/4) (round -17/4) (round 2.5) (round -2.5)]}
@mz-examples[(round 17/4) (round -17/4) (round 2.5) (round -2.5) (round +inf.0)]}
@defproc[(floor [x real?]) integer?]{
@defproc[(floor [x real?]) (or/c integer? +inf.0 -inf.0 +nan.0)]{
Returns the largest integer that is no more than @racket[x].
Returns the largest integer that is no more than @racket[x], but
@racket[+inf.0], @racket[-inf.0], and @racket[+nan.0] floor to
themselves.
@mz-examples[(floor 17/4) (floor -17/4) (floor 2.5) (floor -2.5)]}
@mz-examples[(floor 17/4) (floor -17/4) (floor 2.5) (floor -2.5) (floor +inf.0)]}
@defproc[(ceiling [x real?]) integer?]{
@defproc[(ceiling [x real?]) (or/c integer? +inf.0 -inf.0 +nan.0)]{
Returns the smallest integer that is at least as large as
@racket[x].
Returns the smallest integer that is at least as large as @racket[x],
but @racket[+inf.0], @racket[-inf.0], and @racket[+nan.0] ceiling to
themselves.
@mz-examples[(ceiling 17/4) (ceiling -17/4) (ceiling 2.5) (ceiling -2.5)]}
@mz-examples[(ceiling 17/4) (ceiling -17/4) (ceiling 2.5) (ceiling -2.5) (ceiling +inf.0)]}
@defproc[(truncate [x real?]) integer?]{
@defproc[(truncate [x real?]) (or/c integer? +inf.0 -inf.0 +nan.0)]{
Returns the integer farthest from @racket[0] that is not farther from
@racket[0] than @racket[x].
@racket[0] than @racket[x], but @racket[+inf.0], @racket[-inf.0], and
@racket[+nan.0] truncate to themselves.
@mz-examples[(truncate 17/4) (truncate -17/4) (truncate 2.5) (truncate -2.5)]}
@mz-examples[(truncate 17/4) (truncate -17/4) (truncate 2.5) (truncate -2.5) (truncate +inf.0)]}
@defproc[(numerator [q rational?]) integer?]{