I'm trying to pass a txt file to som_read_data from a GUI......i created a function that takes a txt file from the GUI and then passes it to som_read_data..but i'm getting some errors...here are a list of some of the errors.....any one with ideas?

??? Error using ==> ftell
Invalid file identifier.  Use fopen to generate a valid file identifier.

Error in ==> som_read_data at 169
  fpos1 = ftell(fid); c1 = 0;      % read first non-comment line

Error in ==> prog_som at 3
sD = som_read_data(m);