vech               package:matrixcalc               R Documentation

_V_e_c_t_o_r_i_z_e _a _m_a_t_r_i_x

_D_e_s_c_r_i_p_t_i_o_n:

     This function returns a stack of the lower triangular matrix of a
     square matrix as a matrix with 1 column and n * ( n + 1 ) / 2 rows

_U_s_a_g_e:

     vech(x)

_A_r_g_u_m_e_n_t_s:

       x: a matrix 

_V_a_l_u_e:

     A matrix with n * ( n + 1 ) / 2 rows and one column.

_A_u_t_h_o_r(_s):

     Frederick Novomestky fnovomes@poly.edu

_R_e_f_e_r_e_n_c_e_s:

     Magnus, J. R. and H. Neudecker (1999) Matrix Differential Calculus
     with Applications in Statistics and Econometrics, Second Edition,
     John Wiley.

_S_e_e _A_l_s_o:

     'is.square.matrix'

_E_x_a_m_p_l_e_s:

     x <- matrix( seq( 1, 16, 1 ), nrow=4, byrow=TRUE )
     y <- vech( x )

