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


          | _C_a_l_l_i_n_g _I_n_f_o_r_m_a_t_i_o_n

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

          |      Library: vswtmath (Subsystem mathematical library)


          | _F_u_n_c_t_i_o_n

          |      This   routine  calculates  the  hyperbolic  cosine  of  its
          |      argument,  defined  as  cosh(x)  =  [exp(x)  +   exp(-x)]/2.
          |      Arguments  which  produce  a  value  too  large  for  single
          |      precision storage will signal the error condition.  The con-
          |      dition 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  signal-
          |      led, the default function value 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  algorithm  was  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

          |      dexp$m, Primos signl$


          | _S_e_e _A_l_s_o

          |      dcsh$m (2), dexp$m (2), err$m (2), sinh$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













            cosh$m (2)                    - 1 -                    cosh$m (2)