access data read from file

Trying to read a text file of real numbers into an array, then output the data sequentially as part of a matlab function in Simulink. Main problem is, if I don't initialize the array "RF=zeros(Filesize,1)" the "Output=RF(CountRom/2)" complains "Subscripting into an mxArray is not supported". Setting "Filesize" requires prior knowledge of the length of the file. If "Filesize" is wrong, the fscanf complains that the "read" and "expected" don't match. I'm sure there's a simple solution, just not sure what it is.

function Output = ReadTxt()
    coder.extrinsic('fopen')
    coder.extrinsic('fclose')
    coder.extrinsic('fscanf')

      FileSize = 29866;
      persistent CountRom RF 

      if isempty(CountRom)
          CountRom =  uint32(0);
          RF = zeros(FileSize,1);
          fid = -1;
          fid = fopen('Filename.txt', 'r');
          if (fid > 0)
              RF=fscanf(fid, '%f');
              fclose(fid);
          else
              error('File open failed'); 
          end
      end

      if (CountRom < FileSize)
          CountRom = CountRom + 1; 
          Output = RF(CountRom / 2); % note, RF is base 1

      else
          fclose('all');
          Output = 0;
      end
  end

[Walter Roberson]

You might be able to get further with coder.varsize()

Answer 1

[Prateek Khandelwal]

Have you considered using 'From File' block ? if your aim is to get data from the file at each time step, this might be the solution for you.

Here is the doc link: https://www.mathworks.com/help/matlab/ref/fscanf.html

Answer 2

[F ziegler]

I'm also capturing responses in the same script and both are relative to a mask parameter.