Figure 2.

The recognition accuracy of matrix $S$ with different $c$. s1 denotes the recognition accuracy series with $rank=5$ and $\mu =0.05$. s2 denotes the recognition accuracy series with $rank=5$ and $\mu =0.1$. s3 denotes the recognition accuracy series with $rank=10$ and $\mu =0.05$. s4 denotes the recognition accuracy series with $rank=10$ and $\mu =0.1$.