[racket] "error: degrees->complex: 360.0"

I can't get it to take more than on iteration, either. It's there in 
case I missed something. :)

Neil ⊥

On 05/13/2014 05:59 AM, Robby Findler wrote:
> Thanks, Neil!
>
> Why is the loop needed? I can't seem to get it to take more than one iteration.
>
> Robby
>
> On Mon, May 12, 2014 at 11:24 PM, Neil Toronto <neil.toronto at gmail.com> wrote:
>> He went with exact rationals. Here's another option, which preserves
>> inexactness:
>>
>>      (define (angle->proper-range α)
>>        (let loop ([θ  (- α (* 360 (floor (/ α 360))))])
>>          (cond [(negative? θ)  (loop (+ θ 360))]
>>                [(>= θ 360)     (loop (- θ 360))]
>>                [else  θ])))
>>
>> Its accuracy drops off outside of about [-1e16,1e16].
>>
>> The fact that this is hard to get right might be good motivation for an
>> `flmodulo` function.
>>
>> Neil ⊥
>>
>>
>> On 05/12/2014 09:49 PM, Sean Kanaley wrote:
>>>
>>> Interesting, my code has the same bug then.  I called it modulo/real,
>>> used for things like displaying the space ship's rotation to the user or
>>> wrapping x coordinates to stay in the world.  Apparently it's going to
>>> fail at some point with vector ref out of range.  What was your fix?  I
>>> was thinking to just clamp explicitly like mod/real = (max 0 (min
>>> the-mod-minus-1 (old-modulo/real x)))
>>>
>>>
>>> On Mon, May 12, 2014 at 11:12 PM, Robby Findler
>>> <robby at eecs.northwestern.edu <mailto:robby at eecs.northwestern.edu>> wrote:
>>>
>>>      Right. Probably there is a better fix, but the essential problem, as I
>>>      understand it, is that there are more floating points between 0 and 1
>>>      than between any two other integers and the code made the assumption
>>>      that that didn't happen....
>>>
>>>      The basic desire is to turn a real number into a number in [0,360)
>>>      such that the result represents the same number in degrees but is
>>>      normalized somehow.
>>>
>>>      Robby
>>>
>>>      On Mon, May 12, 2014 at 10:06 PM, Danny Yoo <dyoo at hashcollision.org
>>>      <mailto:dyoo at hashcollision.org>> wrote:
>>>       > Wow.  Floating point really is nasty.  I see how it might have
>>>      happened now.
>>>       >
>>>       > ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
>>>       >> -0.0000000000000001
>>>       > -1e-16
>>>       >> (+ 360 -1e-16)
>>>       > 360.0
>>>       >>
>>>       > ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
>>>
>>>
>>>
>>>
>>> ____________________
>>>     Racket Users list:
>>>     http://lists.racket-lang.org/users
>>>
>>
>> ____________________
>>   Racket Users list:
>>   http://lists.racket-lang.org/users