> Am 01.11.2017 um 17:51 schrieb Greg Titus via swift-dev <swift-dev@swift.org>:
>
> The common (and correct!) wisdom in _any_ programming language that uses IEEE
> floating point is that checking equality of two floating point values is
> almost always a terrible idea. Usually what you want in any real world code
> is to check for a difference less than some epsilon value, which depends upon
> context. There are just too many issues with values that aren’t exactly
> representable, rounding errors during computations, et cetera, for perfectly
> normal floats even if you completely left aside equality rules for NaN.
Quite much what I was about to write about the topic:
I guess the most common difference between a programmer with a graduation and a
autodidact is that one was told that „==" shouldn’t be used with floats,
whereas the other had to learn the hard way.
So, I think it Swift could be really innovative by protecting people from the
trouble of float-equallity — and although that definitely belongs more to
evolution:
I see two possibilities here, and both would rely on generic value parameters.
One is creating a Float type with a parametrized epsilon (or maximal relative
error), the other is using an parametrizing an integer type with a scaling
factor.
Both options are already possible, but as the needed precision depends on the
use case, it imho doesn’t make sense to create a type with a fixed parameter in
the stdlib.
- Tino
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