[jira] Commented: (HAMA-127) Sparse Vector/Matrix

["Edward J. Yoon (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HAMA-127?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12675738#action_12675738 ] 

Edward J. Yoon commented on HAMA-127:
-------------------------------------

= Store Sparse Matrices = 
Sparse Matrices in real applications are usually huge. Much space can be saved if we only store non-zeros.

Space cost for all matrix entries = O(m*n)
Space cost for non-zeros entries = O(t)

Hbase stores the elements with their location (row, column, time). So it provides a good representation.
(I guess we don't need to think more about structure/representation of sparse matrix)

= Add/Mult =
Roughly, I think 'SIMDMultiplyMap' can be used for the sparse matrix multiplication/addition if we only handle an non-zero element. Rests are almost same.

> Sparse Vector/Matrix
> --------------------
>
>                 Key: HAMA-127
>                 URL: https://issues.apache.org/jira/browse/HAMA-127
>             Project: Hama
>          Issue Type: New Feature
>          Components: implementation
>    Affects Versions: 0.1.0
>            Reporter: Edward J. Yoon
>             Fix For: 0.1.0
>
>
> Let's add sparse vector/matrix feature to 0.1

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