Bennett5               package:NISTnls               R Documentation

_M_a_g_e_n_t_i_z_a_t_i_o_n _m_o_d_e_l_l_i_n_g

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

     The `Bennett5' data frame has 154 rows and 2 columns of data from
     a magnetism study

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

       y: A numeric vector of magnetism values. 

       x: A numeric vector of log(time). 

_F_o_r_m_a_t:

     This data frame contains the following columns:

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

     These data are the result of a NIST study involving
     superconductivity magnetization modeling.  The response variable
     is magnetism, and the predictor variable is the log of time in
     minutes.

_S_o_u_r_c_e:

     Bennett, L., L. Swartzendruber, and H. Brown,  NIST (1994).  
     Superconductivity Magnetization Modeling.

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

     data(Bennett5)
     plot(y ~ x, data = Bennett5)

     fm1 <- nls(y ~ b1*(b2+x)**(-1/b3), data = Bennett5,
                start = c(b1 = -2000, b2 = 50, b3 = 0.8), trace = TRUE)

     fm2 <- nls(y ~ b1*(b2+x)**(-1/b3), data = Bennett5,
                start = c(b1 = -1500, b2 = 45, b3 = 0.85), trace = TRUE)
     fm3 <- nls(y ~ (b2+x)**(-1/b3), data = Bennett5, alg = "plinear",
                start = c( b2 = 50, b3 = 0.8), trace = TRUE)
     fm4 <- nls(y ~ (b2+x)**(-1/b3), data = Bennett5, alg = "plinear",
                start = c( b2 = 45, b3 = 0.8), trace = TRUE)

