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.
--
John
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