[ https://issues.apache.org/jira/browse/MAHOUT-1903?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15884686#comment-15884686 ]
ASF GitHub Bot commented on MAHOUT-1903:
----------------------------------------
GitHub user andrewpalumbo opened a pull request:
https://github.com/apache/mahout/pull/286
[MAHOUT-1903][MAHOUT-1907] VCL Vector fix.
After several weeks of discussion with Karl, it turns out that this was a simple fix. Vectors *must* be copied back to MAIN_MEMORY, before trying to read elements out. This seems not to be an issue with Matrices.
Fixed the memory copy issue, however seeing a small numerical error:
```
- VCL Dense Matrix %*% Dense vector *** FAILED ***
2.1868857395626282E-16 was not less than 1.0E-16 (ViennaCLSuiteVCL.scala:346)
+ Mahout dense matrix %*% dense vector multiplication time: 0 ms.
+ ViennaCL/OpenCL dense matrix %*% dense vector multiplication time: 5 ms.
```
Relaxing the assertion by an order of magnitude (-1E16 to -1E15) will solve this problem, however these small numerical differences between the JVM and the Device are interesting and possibly significant for highly iterative algorithms.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/andrewpalumbo/mahout MAHOUT-1903
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/mahout/pull/286.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #286
----
commit 8bda62cace3d1d63a0bda20c94e4e09ea94e3dc4
Author: Andrew Palumbo <***@apache.org>
Date: 2017-02-26T09:25:30Z
fixed the memory copy issue. Tests are failing numerically now
----
Post by Andrew Palumbo (JIRA)Fix VCL vector %*% vector implementation
----------------------------------------
Key: MAHOUT-1903
URL: https://issues.apache.org/jira/browse/MAHOUT-1903
Project: Mahout
Issue Type: Bug
Affects Versions: 0.12.2
Reporter: Andrew Palumbo
Assignee: Andrew Palumbo
Fix For: 0.13.0
Vector %*% vector and vector %*% Matrix need to have memory allocation Re-written. Currently they are commented out in tests
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