code: public static File convertFormat(File matrix, Format current, 
                                       Format desired) throws IOException {
          return convertFormat(matrix, current, desired, false);
      }
docs: Converts the format of the input {@code matrix}, returning a temporary
  file containing the matrix's data in the desired format.
  
  @param matrix a file containing a matrix to convert
  @param current the format of the {@code matrix} file
  @param desired the format of the returned matrix file
  
  @return a matrix file with the same data in the desired format
  
  @throws IOException if any error occurs while reading the input matrix or
  wring the output matrix