trunc() truncates x to an integral value.
                           Entry-Point Names
    Generic                               Compaq
    Function   Data Type   OpenVMS        Tru64 UNIX
    Name       Required    Alpha          Alpha
    trunc      S_FLOAT     math$trunc_s   truncf
               T_FLOAT     math$trunc_t   trunc
               X_FLOAT     math$trunc_x   truncl
               F_FLOAT     math$trunc_f
               G_FLOAT     math$trunc_g