areapoly            package:spatialkernel            R Documentation

_S_i_g_n_e_d _A_r_e_a _o_f _P_o_l_y_g_o_n

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

     Calculate the area of a polygon and its  boundary direction.

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

     areapoly(poly)

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

    poly: matrix containing the 'x,y'-coordinates of the vertices of
          the polygon boundary.

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

    area: positive numeric, the area of the polygon.

    sign: integer, 1 if the polygon orientation is anticlockwise, -1
          otherwise.

    poly: copy of the passed argument 'poly'.

_N_o_t_e:

     This function is provided here so that users do not need to load
     other packages, as it is not available in the base R packages.

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

     Joseph O'Rourke, Computational Geometry in C (2nd Edition),
     Cambridge University Press, 2000 edition.

