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fix the conversion to a [0,360) interval for angles in 2htdp/image

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closes PR 14071
This commit is contained in:
Robby Findler 2013-10-03 19:05:09 -05:00
parent c88e536c46
commit 16778910f5
1 changed files with 10 additions and 3 deletions
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13
pkgs/htdp-pkgs/htdp-lib/2htdp/private/img-err.rkt
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@ -348,8 +348,12 @@
(equal? arg +nan.0)))))
(define (angle->proper-range α)
(+ (modulo (round α) 360)
(- α (round α))))
(define whole-part (modulo (round α) 360))
(define decimal-part (- α (round α)))
(if (and (zero? whole-part)
(negative? decimal-part))
(+ 360 decimal-part)
(+ whole-part decimal-part)))
(module+ test
(require rackunit)
@ -357,4 +361,7 @@
(check-equal? (angle->proper-range 361) 1)
(check-equal? (angle->proper-range 0.5) 0.5)
(check-equal? (angle->proper-range -1) 359)
(check-equal? (angle->proper-range -1.5) 358.5))
(check-equal? (angle->proper-range -1.5) 358.5)
(check-equal? (angle->proper-range -.1) 359.9)
(check-equal? (angle->proper-range #i-7.347880794884119e-016)
(+ 360 #i-7.347880794884119e-016)))