Floating point equality [was Re: What exactly is "exact" (was Clean Singleton Docstrings)]

[Rustom Mody]

On Thursday, July 21, 2016 at 12:04:35 PM UTC+5:30, Steven D'Aprano wrote:
> On Thursday 21 July 2016 15:28, Rustom Mody wrote:
> > BTW APL whose main domain of application is scientific chooses to enshrine
> > this —equality is ε-neighborhood checking not exact equality checking — into
> > its builtin ‘==’
> 
> I have a lot of respect for Ken Iverson, and a lot of admiration for language 
> designers willing to experiment with alternate paradigms.

This choice has significant(!!) costs: Fuzzy equality is not transitive:
One can get
a = b ∧ b = c ∧ a ≠ c
> 
> But keeping in mind that in APL, if you set ⎕ct to 0 you get an exact 
> comparison, can you find any quotes from Iverson saying that you should *never* 
> perform exact equality comparisons?

There you go with your strawmen!
Remember it was you (and Chris) who expressed extreme positions:
“Pernicious myth” “FUD” etc