MATLAB: Is it possible to have a variable length string as an input of the Embedded MATLAB function in MATLAB 7.9 (R2009b)

egsemlcoderMATLAB

I would like to be able to pass a variable length string to my Embedded MATLAB function. This string represents the name of a file which should be opened and can therefore not be of fixed size.

Best Answer

It is possible to specify variable length strings as inputs in Embedded MATLAB. The input argument must be prototyped using the emlcode.egs command. Attached is an example that demonstrates how this can be implemented. In order to build the MEX-file you can use the following line of code:

emlc -eg {emlcoder.egs(char(0), [1, 100])} my_eml_fcn simple.c

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MATLAB: Do I receive an error saying that a variable cannot be found when calling SAVE as an extrinsic function from Embedded MATLAB in Simulink 7.4 (R2009b)

When a call to an extrinsic function is made from an Embedded MATLAB Block, the call is dispatched to MATLAB for execution. Therefore, the variables in the Embedded MATLAB execution environment are not directly available to the MATLAB environment. To enable the execution of the extrinsic function, Embedded MATLAB must transfer necessary variables to the MATLAB environment. In the invocation to SAVE, the input arguments are strings, and not variables. Hence, these strings are transferred to the MATLAB environment, but none of the local variables are.

In order to work around this situation, you must first marshal the required data over to MATLAB and then execute the extrinsic function.

For example:

function save_input(u) %#eml
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assignin('base','u',u); 
save('fromEML.txt','u','-ascii');

MATLAB: Is the FIND function available in the Embedded MATLAB function set in Simulink 7.2 (R2008b)

This change has been incorporated in Simulink 7.4 (R2009b). For previous releases the ability to use the FIND function is not available in the Embedded MATLAB Function set in Simulink 7.1 (R2008a).

A workaround for this is to declare the FIND function extrinsic in an Embedded MATLAB function. For example, the following code declares the MATLAB function FIND extrinsic in the Embedded MATLAB function foo:

function y = foo
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x = ones(4);
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MATLAB: Do I receive an error saying that a variable cannot be found when calling SAVE as an extrinsic function from Embedded MATLAB in Simulink 7.4 (R2009b)

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