[jira] [Commented] (SPARK-22115) Add operator for linalg Matrix and Vector

["Nick Pentreath (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-22115?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16187740#comment-16187740 ] 

Nick Pentreath commented on SPARK-22115:
----------------------------------------

Do we plan to make this private? Or are you suggesting to expose a new public API here?

> Add operator for linalg Matrix and Vector
> -----------------------------------------
>
>                 Key: SPARK-22115
>                 URL: https://issues.apache.org/jira/browse/SPARK-22115
>             Project: Spark
>          Issue Type: Improvement
>          Components: ML, MLlib
>    Affects Versions: 3.0.0
>            Reporter: Peng Meng
>
> For example, there are many code in LDA like this:
> {code:java}
> phiNorm := expElogbetad * expElogthetad +:+ 1e-100
> {code}
> expElogbetad is a breeze Matrix, expElogthetad is a breeze Vector, 
> This code will call a blas GEMV, then loop the result (:+ 1e-100)
> Actually, this can be done with only GEMV, because the standard interface of gemv is : 
> gemv(alpha, A, x, beta, y)        //y := alpha*A*x + beta*y
> We can provide some operators (e.g. Element-wise product (:*), Element-wise sum (:+)) to Spark linalg Matrix and Vector, and replace breeze Matrix and Vector by Spark linalg Matrix and Vector. 
> Then for all the cases like: y = alpha*A*x + beta*y, we can call GEMM or GEMV for it. 
> Don't need to call GEMM or GEMV and then loop the result (for the add) as the current implementation. 
> I can help to do it if we plan to add this feature.  



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