[ruby-core:76312] [Ruby trunk Feature#12217] Introducing Enumerable#sum for precision compensated summation and revert r54237

Issue #12217 has been updated by Akira Tanaka.


Richard Schneeman wrote:
> Would be nice if we could match behavior with Rails Enumerable#sum https://github.com/rails/rails/blob/3d716b9e66e334c113c98fb3fc4bcf8a945b93a1/activesupport/lib/active_support/core_ext/enumerable.rb#L2-L27

I don't like it because the behavior is too complex.

For example, [false].sum returns 0.

It is difficult to document (and understand) the behavior.

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Feature #12217: Introducing Enumerable#sum for precision compensated summation and revert r54237
https://bugs.ruby-lang.org/issues/12217#change-59548

* Author: Kenta Murata
* Status: Closed
* Priority: Normal
* Assignee: Kenta Murata
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In this issue I propose to introduce Enumerable#sum for precision compensated summation of an array of floating point numbers.

In r54237, I've changed Enumerable#inject to support precision compensated summation for summing up floating point numbers.
But I noticed that this commit broke the equality of `ary.inject(:+) == ary.inject {|a, x| a + x }`.
I think this equality is important property of inject method, so I don't want to break it.

And because precision compensated algorithms are complicated, I think they are provided in the standard library, especially simple summation.


---Files--------------------------------
inject-plus.txt (1.21 MB)


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