Function output 'data' cannot be of MATLAB type

function data = readtxt()
   fid = fopen('data_out.txt');
   data=fscanf(fid,'%5d',inf);
   fclose(fid);
end

This Function can run in matlab without any error.But in "Embedded MATLAB Function" of simulink result in some error.

"Function output 'data' cannot be of MATLAB type.

Function 'Embedded MATLAB Function' (#56.0.108), line 1, column 1:
"function data = readtxt()"

"

Answer 1

[Walter Roberson]

Initialize data before assigning to it.

http://www.mathworks.com/matlabcentral/newsreader/view_thread/282262

Michael Hosea wrote,

Your return values are mxArrays and can't mix
with your Embedded MATLAB data. If you know the size and type, you can
pre-declare it, and the compiler will generate the necessary code to convert
an mxArray to a native C data type