How can I create an instance of a class in a method?

I have a class for my needs. It's a simple table of function points.

classdef FuncTable < handle
    %TABLE Class is up to function definition table
    
    properties
        X (1,:) {mustBeNumeric}
        Y (1,:) {mustBeNumeric}
    end
    methods
        function obj = FuncTable(X,Y)
            if (length(X) ~= length(Y))
                throw MException('MATLAB:sizeDimensionsMustMatch', "Размеры массивов в таблице значений отличаются")
            end
    
            obj.X = X;
            obj.Y = Y;
        end
    
        %some definitions here too%
        
    end
end

What I wanna do is to define method diff for this class like this

function dt = diff(t)
    dx = diff(t.X);
    dy = diff(t.Y);
    dt = FuncTable(dx, dy);
end

But! There are no any FuncTable function or variable in a point of view of my class.

Unrecognized function or variable 'FuncTable'.

It's bothering me. I can't find anything about this in the documentation. How can I create an instance of the class in a methods?

Answer 1

[Matt J]

This worked fine for me.

>> t=FuncTable(rand(1,5),rand(1,5))

t =

FuncTable with properties:

X: [0.8712 0.0816 0.8790 0.7562 0.4050]

Y: [0.6144 0.6752 0.8575 0.7428 0.8519]

>> diff(t)

ans =

FuncTable with properties:

X: [-0.7896 0.7974 -0.1228 -0.3512]

Y: [0.0608 0.1824 -0.1148 0.1091]

classdef FuncTable < handle
    %TABLE Class is up to function definition table
    
    properties
        X (1,:) {mustBeNumeric}
        Y (1,:) {mustBeNumeric}
    end
    methods
        function obj = FuncTable(X,Y)
            if (length(X) ~= length(Y))
                throw MException('MATLAB:sizeDimensionsMustMatch', "Размеры массивов в таблице значений отличаются")
            end
    
            obj.X = X;
            obj.Y = Y;
        end


    function dt = diff(t)
        dx = diff(t.X);
        dy = diff(t.Y);
        dt = FuncTable(dx, dy);
    end

    end
end

[Maxim]

Ok, well. I moved class file into root directory and it works for me.

Buf it breaks again if I move class file into +common direcotry.

[Maxim]

Ok. I found an answer. Import statement is needed.

function dt = diff(t)
    import common.*;
    dx = diff(t.X);
    dy = diff(t.Y);
    dt = FuncTable(dx, dy);
end

Your answer was helpful. 10q

[Steven Lord]

The import function's documentation page has this caution on it:

"import PackageName.* adds the contents of the specified package name. PackageName must be followed by .*.

Avoid using this syntax, as importing the contents of packages brings an unspecified set of names into the local scope, which might conflict with names in the MATLAB workspace. One possible use for this syntax is to import a partial package name. Then when you call a function, you use a shorter package name which does not conflict with simple function names."

Your code may break without you making any change to it if any package folder named +common anywhere on the MATLAB path defines a function named diff. Those imported functions would be at level 5 on the function precedence order where the built-in diff function that you intended to call is at level 11.