-----Original Message----- From: Boost [mailto:boost-bounces@lists.boost.org] On Behalf Of degski via Boost Sent: 08 October 2017 13:14 To: boost Cc: degski Subject: Re: [boost] [review] The review of Boost.DoubleEnded starts today: September 21 - September 30
On 28 September 2017 at 14:31, Paul A. Bristow via Boost < boost@lists.boost.org> wrote:
Boost has the floating-point constant phi
http://www.boost.org/doc/libs/1_65_1/libs/math/doc/html/ math_toolkit/constants.html
Expressed as a ratio:
// The Golden Ratio, the ratio of the 2 largest consecutive Fibonacci numbers // representable in std::intmax_t...
#ifdef _WIN64 using golden_ratio = std::ratio<7540113804746346429, 4660046610375530309>; #else using golden_ratio = std::ratio<1836311903, 1134903170>; #endif
Which makes the definition of the Golden Ratio independent of the underlying (system defined) representation of reals, but the best possible.
Boost.Math constants also all provide the best possible representation of reals, but do it * portably over all platforms known to Boost, * at compile time, * constexpr, * and for all Boost.Multiprecision Real types from float up to thousands or decimal digits. But all this is massive overkill when people are uncertain whether 1.5 or 2 is best? When computing a change in capacity I would have thought something integral-ish like 2 or 3/2 would be an advantage? Paul --- Paul A. Bristow Prizet Farmhouse Kendal UK LA8 8AB +44 (0) 1539 561830