On Fri, Jun 17, 2016 at 10:51 AM, John Peterson <jwpeter...@gmail.com>
wrote:
>
>
> On Fri, Jun 17, 2016 at 8:41 AM, David Knezevic <
> david.kneze...@akselos.com> wrote:
>
>> On Fri, Jun 17, 2016 at 10:33 AM, John Peterson <jwpeter...@gmail.com>
>> wrote:
>>
>>>
>>>
>>> On Fri, Jun 17, 2016 at 8:16 AM, David Knezevic <
>>> david.kneze...@akselos.com> wrote:
>>>
>>>> We use TypeVector::relative_fuzzy_equals in a number of places in the
>>>> library. I'm not convinced that this function makes sense, since the
>>>> tolerance effectively depends on where the points happen to be located. I
>>>> can't think of any situation where this behavior is desirable.
>>>>
>>>> My preferred approach is to always use absolute_fuzzy_equals, and to
>>>> use a tolerance that is relative to some reference length, if a
>>>> reference length is available.
>>>>
>>>
>>> Isn't this what relative_fuzzy_equals already does, where the reference
>>> length in question is (||x||_{L1} + ||y||_{L1})? It is implemented in
>>> terms of absolute_fuzzy_equals...
>>>
>>> I guess you are saying that this reference length is rarely the
>>> appropriate choice?
>>>
>>
>> Yeah, that's a bad choice. If both points (x and y) are near the origin,
>> then that tolerance will be super small. If both points are far from the
>> origin the tolerance will be super large.
>>
>> As a result, my preference would be to remove relative_fuzzy_equals from
>> the library.
>>
>
> Your argument makes sense to me but the the fuzzy brothers are Roy's
> babies from nearly 10 years ago,
>
> commit f443e96a460e7d2f7a760fe3ca20bfec0cfc1cfd
> Author: Roy Stogner <royst...@ices.utexas.edu>
> Date: Thu Oct 12 22:09:32 2006 +0000
>
> so he may have envisioned a scenario where both were useful/necessary.
>
OK, I'll be interested to hear Roy's thoughts on this.
David
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