Convert a datatype (like string) into Simple Plain Text like a Matlab Function

Question

Umair Mughal 2020-5-10

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/524482-convert-a-datatype-like-string-into-simple-plain-text-like-a-matlab-function

编辑： Umair Mughal 2020-5-11

Well in programming we have datatypes that tells the compiler how to see the certain variable. And there are built-in functions imported from libraries, compiler see the whole list of functions (like sin, rand) and compile the behine the scene code.

So, if we have a string like "sin(x)", can we convert it into a simple text sin(x). So in this case instead of taking "sin(x)" as a string, compiler identifies it as a built-in function. In app Designer I want a plot a function that user can define from TextField using MATLAB programming, and the only solution I can think of this is that user can also access the MATLAB functions.

Alternatively, we can say can a user add an input as a MATLAB function, or maybe it could be like --> can we change the functions while the program running.

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Ameer Hamza 2020-5-10

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/524482-convert-a-datatype-like-string-into-simple-plain-text-like-a-matlab-function#answer_431641

编辑：Ameer Hamza 2020-5-10

See str2func(): https://www.mathworks.com/help/releases/R2020a/matlab/ref/str2func.html to convert the string to function handle.

For more advanced cases, see feval(): https://www.mathworks.com/help/releases/R2020a/matlab/ref/feval.html and eval(): https://www.mathworks.com/help/releases/R2020a/matlab/ref/eval.html. However, use them with care and also read this: https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval to see that why using them can be a bad idea if used carelessly:

2 个评论
显示无隐藏无

Umair Mughal 2020-5-10

编辑：Umair Mughal 2020-5-11

在 MATLAB Online 中打开

Well thanks, I did it with str2func(); on web I was just missing the proper words for that, and that was easy...

    function main(app)
            s = app.SpeedEditField.Value; % Speed of Animation
            [m1, m2] = Range(app);
            x = m1:0.1:m2;
            try
                f = str2func(strcat('@(x)', app.FunctionEditField.Value));
                y = f(x);
            catch ME
                uialert(app.UIFigure, ME.message, 'Function Error');
                return;
            end
            
            h = animatedline(app.UIAxes);
            
            for k = 1:s:length(x)-s-1
                xvec = x(k:k+(s-1));
                yvec = y(k:k+(s-1));
                addpoints(h, xvec, yvec);
                drawnow
            end
            return;
    end