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https://issues.apache.org/jira/browse/MATH-623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13068275#comment-13068275
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Arne Plöse commented on MATH-623:
---------------------------------
Sorry, I just point out where I think things should go ...
So at first let look at ArrayRealVector.add and then to
(OpenMap|Array)(Real|Field)(Vector|Matrix).(add|subtract|...).
After that wee will see...
{code}
@Override
public RealVector add(RealVector v) {
if (v instanceof ArrayRealVector) {
return add(((ArrayRealVector)v).data);
} else if (v instanceof SparseRealVector){
checkVectorDimensions(v);
double[] out = data.clone();
Iterator<Entry> it = ((SparseRealVector)v).sparseIterator();
Entry e;
while (it.hasNext() && (e = it.next()) != null) {
out[e.getIndex()] += e.getValue();
}
return new ArrayRealVector(out, false);
} else {
final int dim = v.getDimension();
checkVectorDimensions(dim);
ArrayRealVector result = new ArrayRealVector(dim);
double[] resultData = result.data;
for (int i = 0; i < dim; i++) {
resultData[i] = data[i] + v.getEntry(i);
}
return result;
}
}
RealVector addOld(double[] v) {
final int dim = v.length;
checkVectorDimensions(dim);
double[] out = data.clone();
for (int i = 0; i < dim; i++) {
out[i] += v[i];
}
return new ArrayRealVector(out, false);
}
@Override
public RealVector add(double[] v) {
final int dim = v.length;
checkVectorDimensions(dim);
ArrayRealVector result = new ArrayRealVector(dim);
double[] resultData = result.data;
for (int i = 0; i < dim; i++) {
resultData[i] = data[i] + v[i];
}
return result;
}
{code}
> Use implementation of JAMA for ArrayRealVector operators
> --------------------------------------------------------
>
> Key: MATH-623
> URL: https://issues.apache.org/jira/browse/MATH-623
> Project: Commons Math
> Issue Type: Improvement
> Affects Versions: 3.0
> Reporter: Arne Plöse
> Priority: Minor
> Attachments: ArrayRealVector.diff
>
>
> For instance the add(double[] v) fist clones the array, and then adds all
> entries of this.data to the result.
> JAMA uses the following approach create a empty result[] the assign the sum
> of each entry to the result. this is approximately 10 -20 % faster.
> I will provide a patch with some more enhancements/cleanups for this.
> in the test look for XXX:
> the first number is the jama time the second the current algorithm.
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