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Wrong results with cumsum on logical tall array?

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Mathias
Mathias on 30 Nov 2017
Edited: Edric Ellis on 30 Nov 2017
Hello,
I use Matlab 2017b since a few weeks and try to handle big data with tall Arrays. Today i had to find out that cumsum doesn't work properly on (logical) tall Arrays. Still didn't tested it on other tall Arrays than logical. The first pictures shows a Logical Array as tall and as usual logical plotted.
The next picture Shows the cumsum.
As you can see the cumsum on common Logical Array works as expected. The tall doesn't.
I saw this first on a machine with parallel computing Toolbox installed, but it also appears without the Toolbox. How to explain this phenomenon?
Best regards

Accepted Answer

Edric Ellis
Edric Ellis on 30 Nov 2017
Edited: Edric Ellis on 30 Nov 2017
Thanks for reporting this - this is indeed a bug in the tall implementation of cumsum for logical arrays. You can work around this by using
cumsum(double(tallLogicalArray));
This is described in the following bug report: https://www.mathworks.com/support/bugreports/1635821.

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