Why sometimes a matlab function is called without input arguments?

Hi,

I have seen that matlab function like this

function dx = some_name(x, u, p)

is called as following

model = @some_name;

I couldn't understand why it is called without input arguments and how the results will be.

Answer 1

[Stephen23]

"I have seen that matlab function like this function dx = some_name(x, u, p) is called as following model = @some_name;"

That syntax does not call the function.

In fact it defines a function handle: https://www.mathworks.com/help/matlab/function-handles.html

A function handle is a fundamental MATLAB class: https://www.mathworks.com/help/matlab/matlab_prog/fundamental-matlab-classes.html

A function handle creates an object which can be handled just like any other object (e.g. a numeric array, cell array, graphics object, etc.), e.g. passed as an input/output argument or within a function or script. It can be evaluated when required, just like the original function:

fnh = @sin;
fnh(pi/4)

ans = 0.7071

[Steven Lord]

One metaphor for a function handle is that of a phone number. If I want to talk to you while you're in the same room as I am, I can do so directly. If you're not in the same room as I am, I may not be able to talk to you directly. But if I have your phone number, I can call you up and talk to you (basically) wherever you are.

You can execute a function in MATLAB directly or you can "call it on the phone" via its function handle and execute it that way. Using the @ operator is like writing down the function's phone number on a piece of paper. Your phone number on a piece of paper isn't you, but it's a way to contact you.