Read a sudoku in a .sdm file.
X = sudoku_readsdm ( filename , k )
a string representing a file
the index of the sudoku in the collection
a 9-by-9 matrix, with 0 for unknown entries
Read a sudoku in a .sdm and return the matrix X associated, where 0 represent an unknown cell. Lines begining with # are considered as comments and are ignored.
http://www.sudocue.net/fileformats.php