Derivative pij[i,j] wrt vector delta[k].
McCullagh_derivative_pij_wrt_delta_vec(i, j, k, psi, delta_vec, alpha, c = 1)list containing matrices pij and qij
row index of pij
column index of pij
index of delta
the matrix of symmetry parameters
the vector asymmetry parameter
the vector of asymmetry parameters
the normalizing constant for the pis to sum to 1.0 Default value is 1.0