df_ncut

Derivative of minimum normalised cut projection index with respect to projection vector
DF = DF_NCUT(V,X,PARS)

 Inputs:
    (V): projection vector
    (X): N-by-D Data matrix
    (PARS): parameter struct containing 
        (minsize): minimum cluster size and
        (sigma) Scaling parameter for Laplace kernel

 Output: 
    (DF): derivative of Normalised Cut projection index