Built-in and UDT types - including multiprecision user-defined type (UDT)
   floating-point types like NTL, MPFR/GMP, mp_float.

     Accurate - ensuring that the values are as accurate as possible for the
   chosen floating-point type.

     * No loss of accuracy from repeated rounding of intermediate computations.
     * Result is computed with higher precision and only rounded once.
     * Less risk of inaccurate result from functions pow, trig and log at
       [1]corner cases.
     * Less risk of [2]cancellation error.

References

   1. http://en.wikipedia.org/wiki/Corner_case
   2. http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html