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https://issues.apache.org/jira/browse/HAMA-170?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12707294#action_12707294
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Edward J. Yoon commented on HAMA-170:
-------------------------------------
Oh, Thanks.
As you said, "The 1-norm is obtained by finding the sum of the absolute value
of all the elements in each column of the matrix. The largest of these sums is
the 1-norm. In mathematical terms, the 1-norm is simply the maximum absolute
column sum of the matrix."
So, if A = {{1, 3}, {2, 4}} then ||A||1 = max(3, 7) = 7
Comments should be fixed. But, fortunately 1-Norm was correctly implemented as
below.
1-NormMapper:
for(Map.Entry<Writable, Writable> e : value.entrySet()) {
rowSum += Math.abs(((DoubleEntry) e.getValue()).getValue());
}
1-NormReducer:
while (values.hasNext()) {
max = Math.max(values.next().get(), max);
}
> Implementation of Matrix.Norm
> -----------------------------
>
> Key: HAMA-170
> URL: https://issues.apache.org/jira/browse/HAMA-170
> Project: Hama
> Issue Type: Improvement
> Components: implementation
> Affects Versions: 0.1.0
> Reporter: Edward J. Yoon
> Assignee: Edward J. Yoon
> Fix For: 0.1.0
>
>
> enum Norm {
> /** Maximum absolute row sum */
> One,
> /** The root of sum of the sum of squares */
> Frobenius,
>
> /** Largest entry in absolute value */
> Infinity,
>
> /** Largest entry in absolute value. Not a proper matrix norm */
> Maxvalue
> }
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