Effortless - avoiding a search of reference sources.
Usable with both builtin floating point types, and user-defined, possibly
extended precision, types such as NTL, MPFR/GMP, mp_float: in the latter
case the constants are computed to the necessary precision and then cached.
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