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Fix rationalize with +nan.0 tolerance

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Calling `rationalize` with `+nan.0` as the second argument was causing
a "no exact representation error."  This commit changes it to produce
`+nan.0`.

There was an unexercised set of tests for `rationalize` in the test
suite which, once called, demonstrate the bug.

Those tests also specify that `rationalize` should produce an exact
result when the first argument is exact and the second is an infinity.
That's not what the implementation does; it coerces the result to
inexact.  I changed the test cases to match the implementation, which
is consistent with other Schemes (Chez, MIT) and standards (R6RS).
This commit is contained in:
David Van Horn 2020-12-15 21:24:28 -05:00 committed by Matthew Flatt
parent 4fa48182c0
commit c93837c2ce
2 changed files with 6 additions and 6 deletions
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8
pkgs/racket-test-core/tests/racket/number.rktl
View File

@ -2440,16 +2440,16 @@
(err/rt-test (rationalize .3+0.0i 1/10)) (err/rt-test (rationalize .3+0.0i 1/10))
(define (test-rat-inf v) (define (test-rat-inf v)
(define zero (if (exact? v) 0 0.0))
(test +inf.0 rationalize +inf.0 v) (test +inf.0 rationalize +inf.0 v)
(test -inf.0 rationalize -inf.0 v) (test -inf.0 rationalize -inf.0 v)
(test-nan.0 rationalize +nan.0 v) (test-nan.0 rationalize +nan.0 v)
(test zero rationalize v +inf.0) (test 0.0 rationalize v +inf.0)
(test zero rationalize v -inf.0) (test 0.0 rationalize v -inf.0)
(test-nan.0 rationalize v +nan.0)) (test-nan.0 rationalize v +nan.0))
(test-rat-inf 1/3)
(let loop ([i 100]) (let loop ([i 100])
(unless (= i -100) (unless (= i -100)
(test (/ i 100) rationalize (inexact->exact (/ i 100.0)) 1/100000) (test (/ i 100) rationalize (inexact->exact (/ i 100.0)) 1/100000)

4
racket/collects/racket/private/misc.rkt
View File

@ -68,12 +68,12 @@
[lo (- x delta)] [lo (- x delta)]
[hi (+ x delta)]) [hi (+ x delta)])
(cond (cond
[(equal? x +nan.0) x] [(not (= x x)) x]
[(or (equal? x +inf.0) [(or (equal? x +inf.0)
(equal? x -inf.0)) (equal? x -inf.0))
(if (equal? delta +inf.0) +nan.0 x)] (if (equal? delta +inf.0) +nan.0 x)]
[(equal? delta +inf.0) 0.0] [(equal? delta +inf.0) 0.0]
[(not (= x x)) +nan.0] [(not (= within within)) within]
[(<= lo 0 hi) (if (exact? x) 0 0.0)] [(<= lo 0 hi) (if (exact? x) 0 0.0)]
[(or (inexact? lo) (inexact? hi)) [(or (inexact? lo) (inexact? hi))
(exact->inexact (do-find-between (inexact->exact lo) (inexact->exact hi)))] (exact->inexact (do-find-between (inexact->exact lo) (inexact->exact hi)))]