MATLAB: How to implement a MATLAB class that simulates function syntax (like scatteredInterpolant)

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How can I implement a MATLAB class that simulates function syntax (like 'scatteredInterpolant')? For example,
 >> F = MyFunction([91; 13; 92], [64; 10; 28], [55; 96; 97]);
 >> F(1, 2)
 ans =
   101.9511

Best Answer

You can achieve this behavior using operator overloading:
https://www.mathworks.com/help/releases/R2017b/matlab/matlab_oop/implementing-operators-for-your-class.html
Here is an example 'MyFunction' class that simulates a subset of the behavior of 'scatteredInterpolant' by using a private 'scatteredInterpolant' object and overloading the 'subsref' method.
% MyFunction.m
classdef MyFunction
    properties (Access = private)
        F
    end
    methods
        function obj = MyFunction(x, y, v)
            obj.F = scatteredInterpolant(x, y, v);
        end
        function B = subsref(A, S)
            if ~( ...
                    strcmp(S.type, '()') && ...
                    length(S.subs) == 2 && ...
                    isa(S.subs{1}, 'double') && ...
                    isa(S.subs{2}, 'double') && ...
                    all(size(S.subs{1}) == size(S.subs{2})) ...
                    ... % etc.
                )
                error('error: invalid index ...');
            end
            B = A.F(S.subs{1}, S.subs{2});
        end
    end
end
You can use 'MyFunction' as follows.
>> F = MyFunction([91; 13; 92], [64; 10; 28], [55; 96; 97])
F = 
    MyFunction with no properties.
>> F(1, 2)
ans =
    101.9511
>> F([1; 2], [1; 2])
ans =
    103.1101
    102.2278
>> F([1 2], [1 2])
ans =
    103.1101  102.2278
Note that you could implement the 'subsref' method to support multiple numbers and types of indices (as 'scatteredInterpolant' does).
https://www.mathworks.com/help/releases/R2017b/matlab/ref/scatteredinterpolant.html#bvkm1mh
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