error: function definition are not supported in this context. functions can only be created as local or nested functions in code files in matlab

This error occurs when you attempt to define a function in a script. In MATLAB, you can define functions either as their own separate files or as nested functions within other functions.

To resolve this error, move your function definition out of the script and into its own separate function file. Alternatively, you could define the function as a nested function within another function within the script.

Example of a separate function file:

main.m
% myFunction.m

function output = myFunction(input)
    output = input * 2;
end
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6 lines

Example of a nested function within a script:

main.m
% myScript.m

function main()
    x = 10;
    y = multiplyByTwo(x);
    
    function output = multiplyByTwo(input)
        output = input * 2;
    end
end
156 chars
11 lines

In both cases, you can call the function in the Command Window or another script by using the function name followed by parentheses. For example: myFunction(5) or main().