cos$m (2) --- calculate cosine                           04/27/83


          | _C_a_l_l_i_n_g _I_n_f_o_r_m_a_t_i_o_n

          |      longreal function cos$m (x)
          |      real x

          |      Library: vswtmath (Subsystem mathematical library)


          | _F_u_n_c_t_i_o_n

          |      This  function returns the cosine of the angle whose measure
          |      (in radians) is given by the argument.  The  absolute  value
          |      of  the  angle  plus  one-half  pi  must  be  less than than
          |      26353588.0.  The condition SWT_MATH_ERROR$ is  signalled  if
          |      there  is  an argument error.  An on-unit can be established
          |      to deal with this error; the SWT  Math  Library  contains  a
          |      default  handler  named  'err$m' which the user may utilize.
          |      If an error is signalled, the  default  function  return  is
          |      zero.

          |      This  function  is  intended  to serve as a single precision
          |      function although it returns a double precision result.  The
          |      function has been coded so that any value returned will  not
          |      overflow  or  underflow  a  single  precision floating point
          |      value.  The double precision register  overlaps  the  single
          |      precision register so it is possible to declare and use this
          |      function as simply a "real" function.


          | _I_m_p_l_e_m_e_n_t_a_t_i_o_n

          |      The   function   is  implemented  as  a  minimax  polynomial
          |      approximation.  It is adapted from the  algorithm  given  in
          |      the  book  _S_o_f_t_w_a_r_e  _M_a_n_u_a_l  _f_o_r _t_h_e _E_l_e_m_e_n_t_a_r_y _F_u_n_c_t_i_o_n_s by
          |      William Waite and William Cody, Jr.  (Prentice-Hall, 1980).


          | _C_a_l_l_s

          |      dint$p, Primos signl$


          | _S_e_e _A_l_s_o

          |      acos$m (2), dcos$m (2), dint$p (2), err$m (2), sin$m (2),
          |      _S_W_T _M_a_t_h _L_i_b_r_a_r_y _U_s_e_r_'_s _G_u_i_d_e












            cos$m (2)                     - 1 -                     cos$m (2)