Question

I want to save a string with its corresponding index in a matrix but I am getting an error.

Here is a small example:

Mat_=[];            
Val1=[10,19,22,15,30];
Val2=20
Strs_=[];
for i= 1:length(Val1)
if abs(Val1(1,i))<abs(Val2)
            Str_={'Überschritten'};  
        else
            Str_={'Unterschritten'};
end
Strs_=[Strs_;Str_];
Mat_=[Mat_;i];
end
Mat_
Strs_
FMat=[Mat_,Strs_]

Answer 1

You need a cell array to work with strings. To do this, you can preallocate a cell array and fill it.

Val1 = [10,19,22,15,30];
Val2 = 20;
FMat = cell(length(Val1), 2); % Preallocate empty cell array
for idx = 1:length(Val1)
    if abs(Val1(1,idx)) < abs(Val2)
        Str_ = 'Überschritten';  
    else
        Str_ = 'Unterschritten';
    end    
FMat(idx, :) = {idx, Str_};
end

Your FMat cell array will be:

1   'Überschritten'
2   'Überschritten'
3   'Unterschritten'
4   'Überschritten'
5   'Unterschritten'

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Notice that I also changed your loop variable i to idx. In MATLAB, i and j are defined as sqrt(-1). It is always a good idea to give your variables other names.