L = ldl(A)[L,D] = ldl(A)[L,D,P] = ldl(A)[L,D,p] = ldl(A,'vector')[U,D,P] = ldl(A,'upper')[U,D,p] = ldl(A,'upper','vector')[L,D,P,S] = ldl(A)[L,D,P,S] = LDL(A,THRESH)[U,D,p,S] = LDL(A,THRESH,'upper','vector')