What does `@(x) myfun(x, F_index)` means in Matlab?

Question

What does @(x) myfun(x, F_index) means in MATLAB? What does it call and return?

For example in this application:

fmincon(@(x) myfun(x, F_index), ...)

Please provide more examples and explain them if possible.

Answer 1

It is an anonymous function, which is a function that is not stored in a program file, but is associated with a variable whose data type is function_handle. Anonymous functions can accept inputs and return outputs, just as standard functions do. However, they can contain only a single executable statement. For example, create a handle to an anonymous function that finds the square of a number:

    function out=powerplus1(x,dat)
    out=x^2+dat;
     end

In another file you write

dat=1;
sqr = @(x) powerplus1(x,dat);
a = sqrplusone(5)

Then a will be 26.

Variable sqrplusone is a function handle. The @ operator creates the handle, and the parentheses () immediately after the @ operator include the function input arguments. This anonymous function accepts a single input x, and implicitly returns a single output, an array the same size as x that contains the squared plus one values. Find the square plus one of a particular value (5) by passing the value to the function handle, just as you would pass an input argument to a standard function.

a = sqrplusone(5)
a =
   26