function    [dLam,dX] = Fpmus(Fd,Fc,Lam,X,V,H)
X=sparse(X);
V=sparse(V);
H=sparse(H);
Fd=sparse(Fd);
Fc=sparse(Fc);
Lam=sparse(Lam);

dX= sparse(2*KWs(KW(Fd,V,H),V,H)+(1/2)*(Fc'*Lam+Lam*Fc));
dLam = sparse(-Fd + (1/2)*(X*Fc'+Fc*X));
