In some cases, using the same variable to reference different function handles causes a compile-time error. For example, this code does not compile:

function y = foo(p)
x = @plus;
if p
  x = @minus;
end
y = x(1, 2);

You cannot pass function handles as inputs to or outputs from coder.ceval. For example, suppose that f and str.f are function handles:

f = @sin;
str.x = pi;
str.f = f;

The following statements result in compilation errors:

coder.ceval('foo', @sin);
coder.ceval('foo', f);
coder.ceval('foo', str);

You cannot create a function handle that references an extrinsic MATLAB function.

You cannot pass function handles to or from feval and other extrinsic MATLAB functions.

You cannot pass function handles as inputs to or outputs from entry-point functions. For example, consider this function:

function x = plotFcn(fhandle, data)

assert(isa(fhandle,'function_handle') && isa(data,'double'));

plot(data, fhandle(data));
x = fhandle(data);

In this example, the function plotFcn receives a function handle and its data as inputs. plotFcn attempts to call the function referenced by the fhandle with the input data and plot the results. However, this code generates a compilation error. The error indicates that the function isa does not recognize 'function_handle' as a class name when called inside a MATLAB function to specify properties of inputs.