gompertzd                package:drc                R Documentation

_T_h_e _d_e_r_i_v_a_t_i_v_e _o_f _t_h_e _G_o_m_p_e_r_t_z _f_u_n_c_t_i_o_n

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

     'gompertzd' provides a way of specifying the derivative of the
     Gompertz function as a dose-response model.

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

       gompertzd(fixed = c(NA, NA), names = c("a", "b"))

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

   fixed: numeric vector. Specifies which parameters are fixed and at
          what value they are fixed.  NAs for parameter that are not
          fixed.

   names: a vector of character strings giving the names of the
          parameters (should not contain ":"). The default is (notice
          the order): a, b.

_D_e_t_a_i_l_s:

     The derivative of the Gompertz function is defined as


                   f(x) = a exp(bx-a/b(exp(bx)-1))


     For a>0 and b not 0, the function is decreasing, equaling a at x=0
      and approaching 0 at plus infinity.

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

     The value returned is a list containing the model function, the
     self starter function and the parameter names.

_N_o_t_e:

     This function is for use with the function 'drm'.

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

     Christian Ritz

