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How can I stop C MEX s-function from outputting anything?

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I have a C MEX s-function that receives some data, processes it and outputs an array.
I was wondering if there is a way to not output anything (instead of zeros) when the s-function does not receive anything. Inside the s-function I can detect whether anything has been received but I couldn't figure out a way to use this information to inhibit the output (e.g. show nothing when connected to a Display (sink)).

Accepted Answer

Sunny Talekar
Sunny Talekar on 23 Feb 2018
I managed to achieve the desired outcome by configuring the s-function output as variable-size mode and set the current output dimension to 0 when there is nothing to output.

More Answers (1)

Abhi Sundararaman
Abhi Sundararaman on 31 Jul 2017
It shouldn't be possible to remove the output entirely, since if there is an outport on your s-function block, there will always be an output signal.
However, if you want a visual indicator of the output being invalid (basically the same as outputting nothing), you could try outputting "NaN" instead of zeros.
  1 Comment
Sunny Talekar
Sunny Talekar on 31 Jul 2017
The s-function is designed to output an array of uint8s. I tried setting it to NaN, as suggested, using mxGetNaN(), NAN, std::nan but the output either gets limited to 255 or 0. Not sure, if I'm doing it right.

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