MATLAB: Output argument “…” (and maybe others) not assigned during call to “…”.

arrayfunctionfunction calledMATLABmatrixmatrix arrayreadmatrix()txt

I have this error. When I call a function in another function this error pull up:
Output argument "matrix" (and maybe others) not assigned during call to "ChargerMatrice".
Error in OptimiserChemin (line 10)
[matrix] = ChargerMatrice (choixOption);
However when I run the function called only, the Command Window display my matrix correctly.
My function where I call the other function is this one:
function [unChemin,cheminPossible] = OptimiserChemin ()
[tab,tf] = CreerTrajet ();
borne1 = tab(1);
borne2 = tab(2);
autonomie = tab(3);
choixOption = 1;
[matrix] = ChargerMatrice (choixOption); %this line causing the error
matrixDistance = matrix;
choixOption = 2;
[matrix] = ChargerMatrice (choixOption);
matrixDuree = matrix;
distance = matrixDistance(borne1,borne2);
duree      = matrixDuree(borne1,borne2);
and the function called is :
function [matrix] = ChargerMatrice (choixOption)
        if (choixOption == 1)
          file = fopen('MatriceDistances.txt', 'rt');
                 
    
          if file ~= -1
            maintable1 = readmatrix('MatriceDistances.txt');
            maintable1(1,:) = [];
            maintable1(:,1) = [];
            matrix = maintable1; %the variable matrix is there

            fclose(file);
            
            
        elseif (choixOption == 2)
            file = fopen('MatriceDurees.txt', 'rt');
                 
    
          if file ~= -1
            maintable2 = readmatrix('MatriceDurees.txt');
            maintable2(:,1) = [];
            matrix = maintable2; %the variable matrix is there
            fclose(file);
            
            
        else
            fprintf('Erreur! Veuillez choisir un nombre entre 1 et 2 correspondant à la matrice à afficher');
              
          end
          end
        end
end

Best Answer

Your code does not assign anything to matrix in the case that the fopen fails.
Your elseif choixOption == 2 is on the else from file ~= -1, so it will only be executed in the case that choixOption is 1 but the fopen fails. If choixOption is passed in as 2 then there is no else or elseif for that case.
By the way, you can program using try/catch style around readmatrix() instead of testing the file open yourself.
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