Stochastic svd's is not handling well all cases of sparse vectors
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Key: MAHOUT-638
URL: https://issues.apache.org/jira/browse/MAHOUT-638
Project: Mahout
Issue Type: Bug
Components: Math
Affects Versions: 0.5
Reporter: Dmitriy Lyubimov
Assignee: Dmitriy Lyubimov
Fix For: 0.5
The Mahout patch of the algorithm is not handling all types of sparse input
efficiently. BtJob doesn't handle SequentialSparseVector in a way to pick only
non-zero elements from initial input and QJob doesn't iterate over
RandomAccessSparseVector correctly. With extremely sparse inputs (0.05%
non-zero elements) that leads to a terrible inefficiency in the aforementioned
jobs (QJob, BtJob).
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