I was trying to add errors messages if theres error in user input but I ended up with two errors that I couldn't figure it out how to fix

function CalculerButtonPushed(app, event)
          
           
           x=app.ValeurdeXEditField.Value;
           a=str2num(x);

           y=app.fxEditField.Value;
           b=str2num(y);

           z=app.fdeX.Value;
           c=str2num(z);
if (app.ValeurdeXEditField.Value==' ')||(app.fxEditField.Value==' ')||(app.fdeX.Value==' ')
 errordlg("Les vecteurs doivent ",'ERREUR');
else 

if size(a)== size(y)
    n=length(a);
 p0=0;
 for i=1:n
        L=1;
     for j=1:n
         if i~=j
             L=L.*(c-a(j))/(a(i)-a(j));
         end
     end
      p0=p0+(b(i).*L);
 end
   Y=p0;

    app.ResultatdefxTextArea.Value=num2str(Y);

else
    errordlg("Les vecteurs doivent etre de la meme taille ",'ERREUR');
end
end

this is the errors i get:

1)

Error in app2/CalculerButtonPushed (line 37)

if (app.ValeurdeXEditField.Value==' ')||(app.fxEditField.Value==' ')||(app.fdeX.Value==' ')

Error while evaluating Button PrivateButtonPushedFcn.

2)

Index exceeds the number of array elements even if i type the same array size

[Walter Roberson]

I think it might make more sense to isnan(a) and b and c

Answer 1

[prabhat kumar sharma]

Hi @Oumaima Bendidi,

I understand you are facing issues in the button pushed call back function.

1. The error received in the line 37 is likely due to the syntax you are using. You can correct it by using the “isequal” function as follows:

if isequal(app.ValeurdeXEditField.Value,  ' ')|| isequal(app.fxEditField.Value, ' ') ||isequal(app.fdeX.Value, ' ')  
    errordlg("Les vecteurs doivent ",'ERREUR');    

The “isequal” function is used to convert the operands to a logical scalar vector. For more information about the same, you can refer to the following documentation link:

https://mathworks.com/help/releases/R2021b/matlab/ref/isequal.html

2. On executing the provided code, I found another issue where you are trying to compare the sizes of “a” and “y”. Since “a” is a numeric array and “y” is a string array, the sizes will always be different and thus trigger the error dialogue. It can be rectified by comparing the sizes of variables “a” and “b”.

Making the above-mentioned changes resulted in smooth execution of the application.

I hope this helps!

Regards,

Prabhat Sharma

[Walter Roberson]

I wonder if you should be testing

 isempty(app.ValeurdeXEditField.Value) || isempty(app.fxEditField.Value) || isempty(app.fdeX.Value)

or perhaps isempty(strtrim(...))