Input: Data set X R D × n ; The reduced dimension d, parameter p. Output: optimal transformation matrix W R D × d .

1: Initialize W by using LDA [35] ;

2: Repeat step 3-step 5;

3: Update d i j t by using d i j = W T ( x i x j ) 2 p 2 ;

4: Update W t by using the eigenvalue decomposition of Equation (10);

5: t = t + 1 ;

6: Until Convergence;

7: Return transformation matrix W .