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Re: sum array

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Andrew Poulos wrote:

> To sum the integer elements in an array I'm using
> 
> var sum = arr.reduce(function(a, b) {
>    return a + b;
> });
> 
> which is fine. 

Actually, it is NOT.

> […]
>    var arr = [,0, 1, -1, 3,, …];

This approach is (more or less) fine with *those* numbers and in general 
with numbers that require little precision.

But as I learned recently, it is prone to “catastrophic cancellation”
in ECMAScript implementations, too, because they use IEEE-754 “double 
precision” *floating-point* values for numbers by default.

Therefore, I have added implementations of the Kahan–Babuška, Kahan–Babuška–
Neumaier and pairwise summation algorithms to JSX:math/float.js yesterday, 
and I am going to refactor the corresponding methods (e.g. 
JSX:math/algebra.js#jsx.math.Vector.prototype.dot()) to use Kahan–Babuška–
Neumaier summation.

<https://en.wikipedia.org/wiki/Loss_of_significance>

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Thread

sum array Andrew Poulos <ap_prog@hotmail.com> - 2017-11-12 11:09 +1100
  Re: sum array Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-11-12 01:20 +0000
  Re: sum array Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-02-14 09:57 +0100
    Re: sum array "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2018-02-15 12:12 -0800

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