Standard library header <numbers> (C++20)

 

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Standard library headers

Language support
<cstddef> <cstdlib> <version> (C++20) <limits> <climits>	<cfloat> <cstdint> (C++11) <stdfloat> (C++23) <new> <typeinfo>	<source_location> (C++20) <exception> <initializer_list> (C++11) <compare> (C++20)	<coroutine> (C++20) <csignal> <csetjmp> <cstdarg>
Concepts
<concepts> (C++20)
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<stdexcept> <stacktrace> (C++23)	<cassert>	<cerrno>	<system_error> (C++11)
Memory management
<memory>	<memory_resource> (C++17)	<scoped_allocator> (C++11)
Metaprogramming
<type_traits> (C++11)	<ratio> (C++11)
General utilities
<utility> <tuple> (C++11) <optional> (C++17) <variant> (C++17)	<any> (C++17) <expected> (C++23) <bitset>	<functional> <typeindex> (C++11) <execution> (C++17)	<charconv> (C++17) <format> (C++20) <bit> (C++20)
Strings
<string_view> (C++17) <string>	<cctype> <cwctype>	<cstring> <cwchar>	<cuchar> (C++11)
Containers
<array> (C++11) <deque> <forward_list> (C++11) <list>	<vector> <map> <set> <unordered_map> (C++11)	<unordered_set> (C++11) <queue> <stack> <flat_map> (C++23)	<flat_set> (C++23) <span> (C++20) <mdspan> (C++23)
Iterators
<iterator>
Ranges
<ranges> (C++20)	<generator> (C++23)
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<algorithm>	<numeric>
Numerics
<cfenv> (C++11) <complex>	<random> (C++11) <valarray>	<cmath>	<numbers> (C++20)
Time
<chrono> (C++11)	<ctime>
Localization
<locale>	<clocale>	<codecvt> (C++11/17*)
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<iosfwd> <iostream> <ios> <streambuf>	<istream> <ostream> <iomanip> <print> (C++23)	<sstream> <spanstream> (C++23) <fstream> <syncstream> (C++20)	<filesystem> (C++17) <cstdio> <cinttypes> (C++11) <strstream> (C++98*)
Regular expressions
<regex> (C++11)
Concurrency support
<stop_token> (C++20) <thread> (C++11) <atomic> (C++11)	<stdatomic.h> (C++23) <mutex> (C++11) <shared_mutex> (C++14)	<condition_variable> (C++11)   <semaphore> (C++20) <latch> (C++20)	<barrier> (C++20) <future> (C++11)
C compatibility
<cstdbool> (C++11/17/20*)   <ccomplex> (C++11/17/20*)	<ctgmath> (C++11/17/20*)	<cstdalign> (C++11/17/20*)	<ciso646> (until C++20)

 

This header is part of the numeric library.

Mathematical constants (since C++20)

The header <numbers> provides several mathematical constants, such as std::numbers::pi or std::numbers::sqrt2

Synopsis

namespace std::numbers {
  template<class T> inline constexpr T e_v          = /* unspecified */;
  template<class T> inline constexpr T log2e_v      = /* unspecified */;
  template<class T> inline constexpr T log10e_v     = /* unspecified */;
  template<class T> inline constexpr T pi_v         = /* unspecified */;
  template<class T> inline constexpr T inv_pi_v     = /* unspecified */;
  template<class T> inline constexpr T inv_sqrtpi_v = /* unspecified */;
  template<class T> inline constexpr T ln2_v        = /* unspecified */;
  template<class T> inline constexpr T ln10_v       = /* unspecified */;
  template<class T> inline constexpr T sqrt2_v      = /* unspecified */;
  template<class T> inline constexpr T sqrt3_v      = /* unspecified */;
  template<class T> inline constexpr T inv_sqrt3_v  = /* unspecified */;
  template<class T> inline constexpr T egamma_v     = /* unspecified */;
  template<class T> inline constexpr T phi_v        = /* unspecified */;
 
  template<floating_point T> inline constexpr T e_v<T>          = /* see description */;
  template<floating_point T> inline constexpr T log2e_v<T>      = /* see description */;
  template<floating_point T> inline constexpr T log10e_v<T>     = /* see description */;
  template<floating_point T> inline constexpr T pi_v<T>         = /* see description */;
  template<floating_point T> inline constexpr T inv_pi_v<T>     = /* see description */;
  template<floating_point T> inline constexpr T inv_sqrtpi_v<T> = /* see description */;
  template<floating_point T> inline constexpr T ln2_v<T>        = /* see description */;
  template<floating_point T> inline constexpr T ln10_v<T>       = /* see description */;
  template<floating_point T> inline constexpr T sqrt2_v<T>      = /* see description */;
  template<floating_point T> inline constexpr T sqrt3_v<T>      = /* see description */;
  template<floating_point T> inline constexpr T inv_sqrt3_v<T>  = /* see description */;
  template<floating_point T> inline constexpr T egamma_v<T>     = /* see description */;
  template<floating_point T> inline constexpr T phi_v<T>        = /* see description */;
 
  inline constexpr double e          = e_v<double>;
  inline constexpr double log2e      = log2e_v<double>;
  inline constexpr double log10e     = log10e_v<double>;
  inline constexpr double pi         = pi_v<double>;
  inline constexpr double inv_pi     = inv_pi_v<double>;
  inline constexpr double inv_sqrtpi = inv_sqrtpi_v<double>;
  inline constexpr double ln2        = ln2_v<double>;
  inline constexpr double ln10       = ln10_v<double>;
  inline constexpr double sqrt2      = sqrt2_v<double>;
  inline constexpr double sqrt3      = sqrt3_v<double>;
  inline constexpr double inv_sqrt3  = inv_sqrt3_v<double>;
  inline constexpr double egamma     = egamma_v<double>;
  inline constexpr double phi        = phi_v<double>;
}