# GPU - CLArrays, GPUArrays - Extract a Matrix from an Array

**URL:** <https://discourse.julialang.org/t/gpu-clarrays-gpuarrays-extract-a-matrix-from-an-array/23741>\
**Category:** GPU\
**Created:** [May 1, 2019, 5:11pm UTC](https://discourse.julialang.org/t/gpu-clarrays-gpuarrays-extract-a-matrix-from-an-array/23741 "2019-05-01T17:11:57Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![jpsamaroo](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jpsamaroo/32/46804_2.png) [@jpsamaroo](https://discourse.julialang.org/u/jpsamaroo)\
**Post date:** [May 1, 2019, 6:13pm UTC](https://discourse.julialang.org/t/gpu-clarrays-gpuarrays-extract-a-matrix-from-an-array/23741/2 "2019-05-01T18:13:43Z")

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If you don’t mind, could you please read the following post and then edit your post to match its recommendations:

> [@Please read: make it easier to help you](https://discourse.julialang.org/t/psa-make-it-easier-to-help-you/14757):
>
> Welcome to the Julia Discourse! We are enthusiastic about helping Julia programmers, both beginner and experienced. This public service announcement (PSA) outlines best practices when asking for help. Following these points makes it easier for us to help you and more likely you’ll get a prompt, useful answer. Keywords are highlighted to make it easier to refer to specific points. Choose a descriptive title that captures the key part of your question, eg “plots with multiple axes” instead of …

Specifically, having a MWE of what you’re trying to do would be very helpful. All I know is that a return type of `Union{}` means that your kernel throws an error somewhere, but without an MWE I couldn’t tell you where that is.

Also, CLArrays is broken right now; what OS and GPU are you trying to do GPGPU computing with?

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