Matrix.pdMat package:nlme R Documentation _A_s_s_i_g_n _M_a_t_r_i_x _t_o _a _p_d_M_a_t _O_b_j_e_c_t _D_e_s_c_r_i_p_t_i_o_n: The positive-definite matrix represented by 'object' is replaced by 'value'. If the original matrix had row and/or column names, the corresponding names for 'value' can either be 'NULL', or a permutation of the original names. _U_s_a_g_e: ## S3 replacement method for class 'pdMat': matrix(object) <- value _A_r_g_u_m_e_n_t_s: object: an object inheriting from class 'pdMat', representing a positive definite matrix. value: a matrix with the new values to be assigned to the positive-definite matrix represented by 'object'. Must have the same dimensions as 'as.matrix(object)'. _V_a_l_u_e: a 'pdMat' object similar to 'object', but with its coefficients modified to produce the matrix in 'value'. _A_u_t_h_o_r(_s): Jose Pinheiro Jose.Pinheiro@pharma.novartis.com and Douglas Bates bates@stat.wisc.edu _S_e_e _A_l_s_o: 'pdMat','"matrix<-"' _E_x_a_m_p_l_e_s: pd1 <- pdSymm(diag(3)) matrix(pd1) <- diag(1:3) pd1