MATLAB: Do I get a found an mxArray error pointing to a variable that has a value from a function declared as coder.extrinsic

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Why do I get the error "Expected either a logical, char, int, fi, single, or double. Found an mxArray. MxArrays are returned from calls to the MATLAB interpreter and are not supported inside expressions. They may only be used on the right-hand side of assignments and as arguments to extrinsic functions." for 'index= sum(cummu <= randm) +1;'

Sample code:

coder.extrinsic('get_param');

x = get_param(<modelname/block>,'Value');

y = x + 5;

Best Answer

You need to explicitly mention the type for the variable that is receiving values from a function declared as coder.extrinsic. If not, MATLAB will return value of type mxArray.

Sample code's answer:

coder.extrinsic('get_param');

x = double(0);

x = get_param(<modelname/block>,'Value');

y = x + 5;

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When using set_param for the "Value" field of a Constant block, use a character array instead of a double, which is evaluated to the actual value.

This is true of many parameters on other blocks as well.

This is fixed by making the following modification:

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Note that the 0 is enclosed in single quotes, making it a character array.

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It is possible to use code suggestions with ordinary class member functions.

The only difference is you must account for the first method argument being a reference to the class.

The first argument passed to a MATLAB class member function is a reference to the object. In that sense, the following two function calls are equivalent:

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For more information on this, please see:

https://www.mathworks.com/help/matlab/matlab_oop/specifying-methods-and-functions.html

When creating the 'functionsSignatures.json', be sure to include an input for the class object.

Here is an example 'functionsSignature.json' snippet for a class which has static and ordinary member functions:

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In the example, "printString" is static, while "multBy" is a traditional member function.

Moreover, once you have written the JSON file, you can also verify it by executing the following command in the MATLAB Command Window:

>> validateFunctionSignaturesJSON

You will find more information about this function in the documentation:

https://www.mathworks.com/help/matlab/ref/validatefunctionsignaturesjson.html

Best Answer

Related Solutions

MATLAB: Do I get the error “Invalid setting in ‘/‘ for parameter ‘‘.” when calling set_param

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