[jira] [Commented] (NUMBERS-163) Summation and LinearCombination Accumulators

[Matt Juntunen (Jira)]

    [ 
https://issues.apache.org/jira/browse/NUMBERS-163?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17362553#comment-17362553
 ] 

Matt Juntunen commented on NUMBERS-163:
---------------------------------------

I agree that we should keep the static methods. There is no need to instantiate 
an object to perform the computation in the simple cases.

Additionally, I don't see how this addresses my use cases. Specifically, I want 
to replace the use of {{double}} accumulators 
[here|https://github.com/apache/commons-geometry/blob/master/commons-geometry-spherical/src/main/java/org/apache/commons/geometry/spherical/twod/RegionBSPTree2S.java#L173]
 (technically a {{Vector3D}} accumulator) with extended precision accumulators. 
The result would look something like this:
{code:java}
Summation.Accumulator xacc = Summation.accumulator();
Summation.Accumulator yacc = Summation.accumulator();
Summation.Accumulator zacc = Summation.accumulator();

for (final ConvexArea2S area : areas) {
    // ...
    xacc.add(centroidVector.getX());
    yacc.add(centroidVector.getY());
    zacc.add(centroidVector.getZ());
}

Vector3D centroidVectorSum = Vector3D.of(
    xacc.get(),
    yacc.get(),
    zacc.get());
{code}

> Summation and LinearCombination Accumulators
> --------------------------------------------
>
>                 Key: NUMBERS-163
>                 URL: https://issues.apache.org/jira/browse/NUMBERS-163
>             Project: Commons Numbers
>          Issue Type: New Feature
>            Reporter: Matt Juntunen
>            Priority: Major
>
> It would be useful to have simple accumulator classes in {{Summation}} and 
> {{LinearCombination}} to perform extended precision operations on arbitrary 
> collections of values without requiring conversion to {{double[]}}. Ex:
> {code:java}
> Summation.Accumulator sum= Summation.accumulator(1d);
> sum.add(x)
>     .add(y)
>     .add(z)
>    .add(w);
> double sumResult = sum.get();
> LinearCombination.Accumulator comb = LinearCombination.accumulator(1d);
> comb.add(x, scale)
>     .add(y, scale)
>     .add(z, scale)
>     .add(w, scale);
> double combResult = comb.get();
> {code}



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