Subscript indices must either be real positive integers or logicals.while reading data from huge file

Hello!

I have file with this structure

Step 1
0.10190103    
0.10145140    
0.10097524    
0.10050153    
0.10003042    
9.95795131E-02
9.91610140E-02
Step 2
9.81189385E-02
9.75561813E-02
9.80424136E-02
0.10000000    
0.10000000    
9.80617628E-02
9.77829769E-02
...
Step N
0.10000000    
0.10000000    
9.93788019E-02
0.11977901    
0.12290157    
0.12588248    
0.12861508

I need to assemble it in matrix with row:

V1 = [0.10190103    
0.10145140    
0.10097524    
0.10050153    
0.10003042    
9.95795131E-02
9.91610140E-02]

V2 = [9.81189385E-02
9.75561813E-02
9.80424136E-02
0.10000000    
0.10000000    
9.80617628E-02
9.77829769E-02]

...

VN = [0.10000000    
0.10000000    
9.93788019E-02
0.11977901    
0.12290157    
0.12588248    
0.12861508]

I am trying to do it this way:

function Out = readData (In)
  C = strsplit (fileread (In));
  Out = cell(1,1); AtStepcount = false; CurrIndex = 0;

    for I = 1 : length (C)
      if strcmp (C{I}, 'Step'); AtStepcount = true; continue; end
      if AtStepcount
        CurrIndex = str2num(C{I}); Out{CurrIndex} = []; AtStepcount = false;  %#ok<*ST2NM>
        continue
       Out{CurrIndex} = [Out{CurrIndex}; str2num(C{I})]; 
      end

    end
  end

And calling it:

A = readData('res.txt')

But it crushes with: "Subscript indices must either be real positive integers or logicals" or "Cell contents indices must be greater than 0" pointing to line Out{CurrIndex} = [Out{CurrIndex}; str2num(C{I})];

Tested sample file is in attachments. Cannot figure out how to make it work.. Any help will be appreciated. Thank you in advance!