Constants                package:base                R Documentation

_B_u_i_l_t-_i_n _C_o_n_s_t_a_n_t_s

_D_e_s_c_r_i_p_t_i_o_n:

     Constants built into R.

_U_s_a_g_e:

     LETTERS
     letters
     month.abb
     month.name
     pi

_D_e_t_a_i_l_s:

     R has a limited number of built-in constants (there is also a
     rather larger library of data sets which can be loaded with the
     function `data').

     The following constants are available:

        *  `LETTERS': the 26 upper-case letters of the Roman alphabet;

        *  `letters': the 26 lower-case letters of the Roman alphabet;

        *  `month.abb': the three-letter abbreviations for the English
           month names;

        *  `month.name': the English names for the months of the year;

        *  `pi': the ratio of the circumference of a circle to its
           diameter.

_S_e_e _A_l_s_o:

     `data'.

_E_x_a_m_p_l_e_s:

     stopifnot(
      nchar(letters) == 1,
      month.abb == substr(month.name, 1, 3)
     )
     eps <- .Machine$double.eps
     all.equal(pi, 4*atan(1), tol= 2*eps)

     # John Machin (1705) computed 100 decimals of pi :
     all.equal(pi/4, 4*atan(1/5) - atan(1/239), 4*eps)

