Mathematical constants

 

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Numerics library

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Mathematical constants

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Constants (since C++20)

Defined in header <numbers>
Defined in namespace std::numbers
e_v	the mathematical constant e (variable template)
log2e_v	\(\log_{2}e\)log 2e (variable template)
log10e_v	\(\log_{10}e\)log 10e (variable template)
pi_v	\(\pi\)π (variable template)
inv_pi_v	\(\frac1\pi\) 1 π (variable template)
inv_sqrtpi_v	\(\frac1{\sqrt\pi}\) 1 √π (variable template)
ln2_v	\(\ln{2}\)ln 2 (variable template)
ln10_v	\(\ln{10}\)ln 10 (variable template)
sqrt2_v	\(\sqrt2\)√2 (variable template)
sqrt3_v	\(\sqrt3\)√2 (variable template)
inv_sqrt3_v	\(\frac1{\sqrt3}\) 1 √3 (variable template)
egamma_v	the Euler–Mascheroni constant (variable template)
phi_v	the golden ratio Φ constant (\(\frac{1+\sqrt5}2\) 1 + √5 2 ) (variable template)
inline constexpr double e	e_v<double> (constant)
inline constexpr double log2e	log2e_v<double> (constant)
inline constexpr double log10e	log10e_v<double> (constant)
inline constexpr double pi	pi_v<double> (constant)
inline constexpr double inv_pi	inv_pi_v<double> (constant)
inline constexpr double inv_sqrtpi	inv_sqrtpi_v<double> (constant)
inline constexpr double ln2	ln2_v<double> (constant)
inline constexpr double ln10	ln10_v<double> (constant)
inline constexpr double sqrt2	sqrt2_v<double> (constant)
inline constexpr double sqrt3	sqrt3_v<double> (constant)
inline constexpr double inv_sqrt3	inv_sqrt3_v<double> (constant)
inline constexpr double egamma	egamma_v<double> (constant)
inline constexpr double phi	phi_v<double> (constant)

Notes

A program that instantiates a primary template of a mathematical constant variable template is ill-formed.

The standard library specializes mathematical constant variable templates for all floating-point types (i.e. float, double and long double).

A program may partially or explicitly specialize a mathematical constant variable template provided that the specialization depends on a program-defined type.