

GammaDist {base}                             R Documentation

_T_h_e _G_a_m_m_a _D_i_s_t_r_i_b_u_t_i_o_n

_U_s_a_g_e_:

     dgamma(x, shape, scale=1)
     pgamma(q, shape, scale=1)
     qgamma(p, shape, scale=1)
     rgamma(n, shape, scale=1)

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

     x,q: vector of quantiles.

       p: vector of probabilities.

       n: number of observations.

shape, scale: shape and scale parameters.

_V_a_l_u_e_:

     These functions provide information about the gamma
     distribution with parameters `shape' and `scale'.
     `dgamma' gives the density, `pgamma' gives the distri-
     bution function `qgamma' gives the quantile function
     and `rgamma' generates random deviates.

     If `scale' is omitted, it assumes the default value of
     `1'.

     The gamma distribution with parameters `shape' = a and
     `scale' = b has density

            f(x) = 1/(b^a Gamma(a)) x^(a-1) e^-(x/b)

     for x > 0, a > 0 and b > 0.

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

     `gamma' for the gamma function, `dbeta' for the beta
     distribution and `dchisq' for the chi-square distribu-
     tion which is a special case of the gamma distribution.

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

     -log(dgamma(1:4, shape=1))
     p <- (1:9)/10
     pgamma(qgamma(p,shape=2), shape=2)
     1 - 1/exp(qgamma(p, shape=1))

