Sudoku Solver

This function will solve the standard 9 by 9 sudoku matrix

Input the partially filled problem as a 9 by 9 matrix and the out put will be given.
Uses a simple greedy and back tracking algorithm.
No error correction is done so please make sure that the inputs are valid
Blank squares of the puzzle should be given an input of value zero '0'.

Sample Input:
sudoku9([1 0 0 0 6 0 0 0 0; 0 0 0 0 0 0 7 8 2;0 0 0 0 4 2 0 0 9;0 7 0 0 0 0 4 0 0;6 0 0 5 0 8 0 0 3;
0 0 8 0 0 0 0 9 0;9 0 0 7 3 0 0 0 0;2 5 6 0 0 0 0 0 0;0 0 0 0 9 0 0 0 6])