Matlab function doesnt run when called from AppDesigner

Question

Sara Rodriguez 2021-11-14

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1586489-matlab-function-doesnt-run-when-called-from-appdesigner

评论： Sara Rodriguez 2021-11-16

I have a problem in which if I call a function from Command Window it functions properly, but when I call it from App Designer it says there is a mistake in the matrix multiplication dimensions. I think this is very weird, because if there was a mistake related to a matrix shouldn't it show in both modes??? I've been using it from command line for a while and its been working fine, Im not sure why it doesnt run from AppDesigner.

This is the code :

function [resultCode, resultX1, resultX2, Z] = busquedas_function(Xo, Delta, Iter, Fun)
resultCode = 0;
% 1 = success
% 2 = failed
%input es un comando de solicitud de entrada de datos del usuario.
f=inline(Fun);
Yo=f(Xo);
if Yo==0
    fprintf('\n\nSOLUCION:\n');
    fprintf ('Xo es raiz\n\n');
else
    X1=Xo+Delta;
    Cont=1;
    Y1=f(X1);
    Z=[Cont,Xo,Yo,(Yo.*Y1)];
    %Z es una matriz la cual permitira observar lo datos como una tabla a la
    %finalizacion del programa
    %La sentencia While ejecuta todas las órdenes mientras la expresión sea
    %verdadera.
    while (((Yo*Y1)>0) & (Cont<Iter ))
        Xo=X1;
        Yo=Y1;
        X1=Xo+Delta;
        Y1=f(X1);
        Cont=Cont+1;
        Z(Cont,1)=Cont;
        Z(Cont,2)=Xo;
        Z(Cont,3)=Yo;
        Z(Cont,4)=Yo*Y1;
        %las z son las posiciones asignadas en la tabla a los resultados que se
        % observarán
    end
    if Y1==0
        fprintf('\n\nSOLUCION:\n')
        fprintf('%g es raiz\n\n',X1)
        resultX1 = X1;
        resultX2 = X1;
    else
        if Yo*Y1<0
            fprintf('\n\nSOLUCION:\n')
            fprintf ('El intervalo que contiene la raíz es[%g,%g]\n\n',Xo,X1)
            resultCode = 1;
            resultX1 = Xo;
            resultX2 = X1;
            
        else
            fprintf('\n\nSOLUCION:\n')
            fprintf ('Fracaso en %g iteraciones\n\n',Iter)
            resultCode = 2;
            resultX1 = 0;
            resultX2 = 0;
        end
    end
end
fprintf('TABLA\n\nIteraciones                 Xo                  Yo                  Yo*Y1 \n\n');
disp(Z);
%La funcion disp permite visualizar la tabla, obtenida de los resultados de
%la secuencia while
ezplot(f);
%El comando ezplot permite grafica una función.
end

if I call it from command line it runs correctly

But calling it with same parameters from App Designer brings up this error:

"Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 1-by-11.

Error in busquedas_function (line 40)

Z(Cont,3)=Yo;"

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Sara Rodriguez 2021-11-15

I checked and by putting values on inside the App Designer code it does work (2nd commented line)

However I'm not sure why my Edit Fields are not passing the arguments as they should.

I double checked and Xo, Delta and Iter are numeric values as they should,Funcion is a text field, since I have funcion as a string I thought I needed to convert it to a char vector, so I tried converting it with:

Fun = app.FuncionEditField.Value

Func = convertStringsToChars(Fun) )

so Im a bit confused as to where is the bad casting.

I mean, it would seem like its the same data, at least to my clueless self.

Dave B 2021-11-15

编辑：Dave B 2021-11-15

在 MATLAB Online 中打开

Are you sure your editfield values are numbers and not characters that contain numbers? If I do:

h=uieditfield;

And then type the number 0.5 in there, and then do h.Value, I get '0.5' not 5. I think you want str2num (I previously wrote num2str by accident sorry!)

Xo = str2num(app.XoEditField.Value);
Delta = str2num(app.DeltaEditField.Value);
Iter = str2num(app.IteraEditField.Value);

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Answer 1

Dave B 2021-11-15

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1586489-matlab-function-doesnt-run-when-called-from-appdesigner#answer_831404

在 MATLAB Online 中打开

You're passing in characters containing numbers the values instead of the values themselves. Use str2num to convert before calling your function.

Xo = str2num(app.XoEditField.Value);
Delta = str2num(app.DeltaEditField.Value);
Iter = str2num(app.IteraEditField.Value);

For a robust app you might want to also validate that they are values before calling the function. You could do this with by checking the result of calling str2num, or by introducing an arguments block (with the mustBeNumeric validator) into busquedas_function.

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Sara Rodriguez 2021-11-15

在 MATLAB Online 中打开

I am very grateful for the explanation, it has helped me understand all of matlab concepts a lot better!

The argument block seems super useful and I implemented it right away!! Thanks a lot, however, it has not seemed to fix my original issue, sadly, as of now my function looks like this:

function SubmitButtonPushed(app, event)
            Xo = str2double(app.XoEditField.Value);
            Delta = str2double(app.DeltaEditField.Value);
            Iter = str2double(app.IteraEditField.Value);
            Fun = convertStringsToChars(app.FuncionEditField.Value);
            % [resultCode, resultX1, resultX2, Z] = busquedas_function(-5,0.5,20,'x*x*x+4*x*x-10')
             [resultCode, resultX1, resultX2, Z] = busquedas_function(Xo,Delta,Iter,Fun);
            
            app.Resultadox1EditField.Value = resultX1;
            app.Resultadox2EditField.Value = resultX2;
            app.SuccessEditField.Value = resultCode;
        end

But the problem persists, same warning:

        Error using *
        Incorrect dimensions for matrix multiplication. Check that the number of columns in the first matrix matches the number of rows in the second matrix. To perform elementwise multiplication, use '.*'.
        
        Error in busquedas_function (line 42)
        while (((Yo*Y1)>0) & (Cont<Iter ))

I already applied the arguments to my function like this:

function [resultCode, resultX1, resultX2, Z] = busquedas_function(Xo, Delta, Iter, Fun)
arguments
    Xo double
    Delta double
    Iter double
    Fun char
end

So Im again a bit confused as to why it seems to recognize some value as a matrix or similar?

Dave B 2021-11-15

在 MATLAB Online 中打开

I'm so sorry, I was sure that was the source of the problem! But I'm sure we can solve it.

To restate where we are...

We know it works when called as:

busquedas_function(-5,0.5,20,'x*x*x+4*x*x-10')

but not as

busquedas_function(Xo,Delta,Iter,Fun);

So it's clear that at least one of these values is different, right?

It seems like now might be a good time to learn about MATLAB breakpoints! If you click on the left side of the editor window, at the line where it fails (line 42), you should see a red box. When you run the code (click on the button) MATLAB will pause at that moment. Then you can examine Yo and Y1 (you can hover over the variables, or look in the Workspace area, or just type them in at the command prompt). Is one of them empty? is one of them not scalar? When your down you can click Quit Debugging at in the toolstrip.

This will likely give a strong hint as to what's going on.

In reality I'd probably actually just set my breakpoint in app designer, clicking on the left side of the app designer code view window just before busquedas_function is called, as we know that everything works okay here with hard coded values but not with the variables. You can even run code at this paused point, like Xo==-5 etc.

Here's more info on breakpoints which will show you what they should look like (though if memory serves me correctly they appear slightly different in the App Designer editor from the regular MATLAB editor) https://www.mathworks.com/help/matlab/matlab_prog/set-breakpoints.html

Side note - for the arguments block I probably would have done something like:

Xo (1,1) double {mustBeNumeric}

Because this guarantees that it's numeric, and scalar. But this is maybe something to tweak after the code is working!

Sara Rodriguez 2021-11-15

在 MATLAB Online 中打开

I got this info while trying to use the breakpoints!

Error using  * 
Incorrect dimensions for matrix multiplication. Check that the number of columns in the first matrix matches the number of rows in the second matrix. To perform elementwise multiplication,
use '.*'.
Error in busquedas_function (line 42)
    while (((Yo*Y1)>0) & (Cont<Iter ))
Error in BusquedaIncremental/SubmitButtonPushed (line 42)
             [resultCode, resultX1, resultX2, Z] = busquedas_function(Xo,Delta,Iter,Fun);
Related documentation
 
228                 throw(callbackException);
In workspace belonging to matlab.apps.AppBase>@(source,event)tryCallback(appdesigner.internal.service.AppManagementService.instance(),app,callback,requiresEventData,event) (line 37)
Interrupt while evaluating Button PrivateButtonPushedFcn.
42               [resultCode, resultX1, resultX2, Z] = busquedas_function(Xo,Delta,Iter,Fun);
2   arguments
Xo =
   NaN
Yo =
    'x*x*x+4*x*x-10'

I checked (hovering over the variables at the paused execution moment) and the function call from app designer is passing the values of Xo, Delta and Iter as NaN , so when it tries to evaluate the f function in Xo its creating the weird matrix we've been seeing!

"Fun" seems to be passing fine for now on the other hand

Im a bit shocked thats the issue, I don't know why its been passing as Nan.

Dave B 2021-11-16

编辑：Dave B 2021-11-16

Ah Sara I feel horrible that I led you down the wrong path to begin with, it's been forever since I've seen someone using inline, I should have spotted it right away! (but ' is so small!)

Sara Rodriguez 2021-11-16

Nooo, don't worry, I barely know what I'm doing and you've been very patient explaining what may be wrong with examples and everything! I'm very grateful!

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