Returns the given sudoku as a sdk string.
str = sudoku_writesdk ( X ) str = sudoku_writesdk ( X , filename )
a 9-by-9 matrix, with 0 for unknown entries
a string representing a file
a 9x9 matrix of characters, with dots "." for unknowns. The entries come row by row.
Converts a sudoku in matrix form into a sdk string, where "." represents unknowns. If the input argument filename is present, also writes the string into the file.
http://www.sudocue.net/fileformats.php