Question

How to test/validate a variable is a function handle in matlab ?

it may be something like:

f=@(x)x+1
isFunctionHandle(f)

the is* build-in functions seems not support these kind testing? anyone know? many thanks

Answer 1

The right way is indeed by means of an is* function, namely isa:

if isa(f, 'function_handle')
    % f is a handle
else
    % f is not a handle
end

edit:
For completeness, I’d like to point out that using class() works for checking if something is a function handle.
However, unlike isa, this doesn’t generalize well to other aspects of MATLAB such as object-oriented programming (OOP) that are having an increasing impact on how MATLAB works (e.g. the plot functionality, the control toolbox, the identification toolbox, … are heavily based on OOP).

For people familiar with OOP: isa also checks the super types (parent types) of the x object for someClass, while strcmp(class(x), 'someClass') obviously only checks for the exact type.

For people who don’t know OOP: I recommend to use isa(x, 'someClass') instead of strcmp(class(x), 'someClass') as that is the most convenient (and commonly useful) behavior of the two.