j0() and j1()  return the value of the Bessel function of the
    first kind of orders 0 and 1, respectively.

    jn() returns the value of the Bessel function of the first kind
    of order n.

    y0() and y1()  return the value of the Bessel function of the
    second kind of orders 0 and 1, respectively.

    yn() returns the value of the Bessel function of the second kind
    of order n.

    The value of x must be positive for the y family of Bessel
    functions. The value of n specifies some integer value.

                           Entry-Point Names

    Generic
    Function   Data Type   OpenVMS        Tru64 UNIX
    Name       Required

    j0         S_FLOAT     math$j0_s      j0f
               T_FLOAT     math$j0_t      j0
               X_FLOAT     math$j0_x      j0l
               F_FLOAT     math$j0_f
               G_FLOAT     math$j0_g

    j1         S_FLOAT     math$j1_s      j1f
               T_FLOAT     math$j1_t      j1
               X_FLOAT     math$j1_x      j1l
               F_FLOAT     math$j1_f
               G_FLOAT     math$j1_g

    jn         S_FLOAT     math$jn_s      jnf
               T_FLOAT     math$jn_t      jn
               X_FLOAT     math$jn_x      jnl
               F_FLOAT     math$jn_f
               G_FLOAT     math$jn_g

    y0         S_FLOAT     math$y0_s      y0f
               T_FLOAT     math$y0_t      y0
               X_FLOAT     math$y0_x      y0l
               F_FLOAT     math$y0_f
               G_FLOAT     math$y0_g

    y1         S_FLOAT     math$y1_s      y1f
               T_FLOAT     math$y1_t      y1
               X_FLOAT     math$y1_x      y1l
               F_FLOAT     math$y1_f
               G_FLOAT     math$y1_g

    yn         S_FLOAT     math$yn_s      ynf
               T_FLOAT     math$yn_t      yn
               X_FLOAT     math$yn_x      ynl
               F_FLOAT     math$yn_f
               G_FLOAT     math$yn_g