How to get 2-variable function from a GUI textbox?

Question

Peter weber 2015-9-1

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https://ww2.mathworks.cn/matlabcentral/answers/238809-how-to-get-2-variable-function-from-a-gui-textbox

编辑： Peter weber 2015-9-2

Hey

I need to input a 2 variable function like f(x,y) and give x and y lower and upper limit and use numerical methods on it. I did it for 1 variable function(find a GUI) but now there are problems with f(x) turnning into f(x,y) and fevel(fx,x) that cannot be (fx,x,y).

here is .m file and the problem area:

x1 = str2double(get(handles.editx1,'String'));
x2 = str2double(get(handles.editx2,'String'));
fx = vectorize(inline(get(handles.editfunc,'String')));
x = [x1:0.001:x2];
values = feval(fx,x);
maxi=max(values);
mini=(min(values));
if mini > 0
      mini = 0;
end;
method = get(handles.pop_int,'Value');

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Answer 1

Walter Roberson 2015-9-2

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https://ww2.mathworks.cn/matlabcentral/answers/238809-how-to-get-2-variable-function-from-a-gui-textbox#answer_191034

在 MATLAB Online 中打开

Why not? feval() accepts multiple arguments. And you don't need feval() anyhow for this purpose.

I recommend that you stop using inline() and start using str2func()

fx = str2func(['@(x,y)' vectorize(get(handles.editfunc,'String'))]);
values = fx(x, y);

I suspect you will also be wanting to use ndgrid() to construct the arguments you pass to your function.

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Walter Roberson 2015-9-2

Remove the last 'end' from textresult_CreateFcn

Peter weber 2015-9-2

编辑：Peter weber 2015-9-2

Thanks again but I have another Questions If I may: I want to use I = trapz(y,trapz(x,F,2)) with the above fx=fx(x,y) but it doesn't work... 2. remember that function you mentioned above fx(x,y), how can I change for instance "x" into " a*x+b" or even entirely something else like 5*t-9...greatly thankful in advance

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