Simulink: Matlab Embedded Function Code Error

Question

I have the following code in an embedded matlab function in simulink:

 function rad = fcn(lenkwinkel)
if lenkwinkel < 0
    rad=[0 1 0 0];
elseif lenkwinkel > 0
    rad=[1 0 0 0];
else
    rad=[0 0 0 0];
end

In the simulation I have the "lenkwinkel" variable connected to the MATLAB Function Block,which is connected to a Mux block with 4 ports.

I am trying to use the function to send a vector with 4 binary elements to the Mux block, which then should split it into 4 signals. Unfortunately, this is not working. When I try to run this, I get:

Inferred size ('[1 4]') for data 'rad' (#44) does not match back propagated size ('[4]') from Simulink.

Can anyone help me with this? Thanks a lot.

Do you mean DeMux? If the demux is connect to a Scope then the model as described works for me (in R2013b). What do you have connected to the output of the demux? — Phil Goddard
– Phil Goddard, Commented Apr 7, 2014 at 14:30
Hello there. Yes, I am sorry. I do mean DeMux. On the left side, the DeMux connects to the function and on the right side it splits into 4 port, where each connects to a product block. Thanks. — thephphero
– thephphero, Commented Apr 8, 2014 at 10:47

Ryan Livingston · Accepted Answer · 2014-04-07 19:11:57Z

2

I am assuming you mean DeMux as well, please correct us if that is incorrect. From the looks of it, the MATLAB Function block has determined that the size of rad is 1-by-4 since that is the size of the value assigned to it. However, something else seems to think that the output should be of size [4] or 4-by-1. Have you manually specified the output of the MATLAB Function block to have size [4] or the size of the demux to expect an input of size [4]?

You could either change the definition of rad to be 4-by-1 or the size specified to Simulink to be [1, 4].

answered Apr 7, 2014 at 19:11

Ryan Livingston

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2 Comments

thephphero Over a year ago

I see what you mean. I didn't know I had to manually set the output of the MATLAB function. Right-clicking the function block, selecting "Explore" and setting the output size to "[1 4]" did the trick. Thanks.

craq Over a year ago

that works for me, but I'd prefer if the output size could be 'Inherited'. Do you have a suggestion for that? (Or is that a separate question?) Also... do you have any idea why taking a transpose doesn't solve the problem?

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