What does "@" do ?

So this is a simple question. I found some code that uses "@" and I looked it up in the matlab documentation, but I did not find it to be really helpfull. Can somebody explain to me what it does and when/how I want to use it ?

Answer 1

[Vandana Rajan]

Hi,

You might have seen function handles.

A function handle is a MATLAB® data type that stores an association to a function.

To create a handle for a function, precede the function name with an @ sign. For example, if you have a function called myfunction, create a handle named f as follows:

>> f = @myfunction;

Now if you have a function like

function y = computeSquare(x)
y = x.^2;
end

>> f = @ComputerSquare;

>> a = 4;

>> b = f(a)

will give

b = 16

Please go through these 2 documentation links which very clearly explains about function handles.

1. https://www.mathworks.com/help/matlab/matlab_prog/creating-a-function-handle.html

2. https://www.mathworks.com/help/matlab/matlab_prog/anonymous-functions.html

Yet another use of the symbol '@' is as class folder designator. An @ sign can indicate the name of a class folder, such as

\@myclass\get.m

See the below link for more info.

https://www.mathworks.com/help/matlab/matlab_oop/organizing-classes-in-folders.html

[H ZETT M]

so basically everything it does is giving me the possibility to "rename" my function ?

[Vandana Rajan]

Not exactly. There are some advantages too.

1. While creating a function, you write it in a .m file and save it in the MATLAB path somewhere. But Anonymous functions can be created from the command line without a script.

2. A function handle can point to a function that is not in scope at the time of execution. For example, the function can be a subfunction in another M-file.

Please use these links for more insight into the advantages of using function handles and anonymous functions

https://en.wikibooks.org/wiki/MATLAB_Programming/Portable_Functions http://matlab.izmiran.ru/help/techdoc/creating_plots/hg_obj48.html

[wejden hammami]

did you know the equivalent of @ in python ?

[Walter Roberson]

https://stackoverflow.com/questions/5743291/python-function-handle-ala-matlab/10941428

[Stephen23]

"did you know the equivalent of @ in python ?"

They are not needed in Python: unlike MATLAB every function must be called using parentheses (even if they contain no inputs), and so the function name (without parentheses) can simply be passed around as a variable (e.g. as input argument, assigned to another variable, etc.). You don't need to add anything else, just use the function name.

[Eun-Mo Son]

Good. Cheers

[tuan nguyen minh]

thanks so much. where can i find more example like this?

[tuan nguyen minh]

i need more example or can you explain it to me?

FuFu=@(t, u1, u2)([u2, 4*t-2*u1-(4/5)*u2]);  
function f=RK_ex1(t, u1, u2)
f = [u2,4*t-2.0*u1-(4/5)*u2];
end  

[Walter Roberson]

https://www.mathworks.com/help/matlab/math/parameterizing-functions.html

[Rockford]

It should be computeSquare, not ComputerSquare.

Answer 2

[Amir Azadeh Ranjbar]

its function handle

func = @(x) x*2+10

func = function_handle with value:
    @(x)x*2+10

func(5)

ans = 20

[Walter Roberson]

Yes, as was explained by @Vandana Rajan 6 years ago.

[Amir Azadeh Ranjbar]

Well, this answer that was given (6 years ago) is more confusing....

[Dyuman Joshi]

What makes you think it is confusing? (let alone more confusing)

And your answer does not mention important details that the accepted answer provides.