| Common mathematical functions | |||||||||||||||||||||||||||||||
| Mathematical special functions(C++17) | |||||||||||||||||||||||||||||||
| Mathematical constants(C++20) | |||||||||||||||||||||||||||||||
| Basic linear algebra algorithms(C++26) | |||||||||||||||||||||||||||||||
| Data-parallel types (SIMD)(C++26) | |||||||||||||||||||||||||||||||
| Floating-point environment(C++11) | |||||||||||||||||||||||||||||||
| Complex numbers | |||||||||||||||||||||||||||||||
Numeric array (valarray) | |||||||||||||||||||||||||||||||
| Pseudo-random number generation | |||||||||||||||||||||||||||||||
| Bit manipulation(C++20) | |||||||||||||||||||||||||||||||
| Saturation arithmetic(C++26) | |||||||||||||||||||||||||||||||
| Factor operations | |||||||||||||||||||||||||||||||
|
| ||||||||||||||||||||||||||||||
| Interpolations | |||||||||||||||||||||||||||||||
|
| ||||||||||||||||||||||||||||||
| Generic numeric operations | |||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||
| C-style checked integer arithmetic | |||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||
Defined in header <valarray> | ||
template<class T> std::valarray<T> pow(conststd::valarray<T>& base,conststd::valarray<T>& exp); | (1) | |
template<class T> std::valarray<T> pow(conststd::valarray<T>& base, | (2) | |
template<class T> std::valarray<T> pow(consttypenamestd::valarray<T>::value_type& vbase, | (3) | |
Raises a value to a power.
The behavior is undefined ifbase.size()!= exp.size().
Contents |
| base | - | numeric array containing the values of the base |
| exp | - | numeric array containing the values of the exponent |
| vbase | - | a value defining the base |
| vexp | - | a value defining the exponent |
A numeric array containing the results of exponentiation.
Unqualified function (pow) is used to perform the computation. If such function is not available,std::pow is used due toargument-dependent lookup.
The function can be implemented with the return type different fromstd::valarray. In this case, the replacement type has the following properties:
#include <cmath>#include <cstddef>#include <iomanip>#include <iostream>#include <valarray> class show{friendstd::ostream& operator<<(std::ostream& os, showconst& r){constexprcharconst* sup[]{"\u2070","\u00B9","\u00B2","\u00B3","\u2074","\u2075","\u2076","\u2077","\u2078","\u2079"}; for(std::size_t n=0; n!= r.bases.size();++n){ os<<std::left<< r.bases[n]<<std::left;if(n< r.exponents.size()) os<< sup[r.exponents[n]%10]<<' ';else os<<" ";} if(r.results.size()!=0){ os<<'=';for(std::size_t n=0; n!= r.results.size();++n) os<<' '<< r.results[n];} return os<<'\n';} public:std::valarray<int> bases{}, exponents{}, results{};}; int main(){constexprint base{2};constexprint exponent{5};conststd::valarray<int> bases{1,2,3,4,5,6,7};conststd::valarray<int> exponents{0,1,2,3,4,5,6};conststd::valarray<int> powers1=std::pow(bases, exponents);conststd::valarray<int> powers2=std::pow(bases, exponent);conststd::valarray<int> powers3=std::pow(base, exponents); std::cout<<"pow(const std::valarray<T>& base, const std::valarray<T>& exp); (1)\n"<<"base : "<< show{bases}<<"exp : "<< show{exponents}<<"pow : "<< show{bases, exponents, powers1}<<'\n'<<"pow(const std::valarray<T>& base, const value_type& vexp); (2)\n"<<"base : "<< show{bases}<<"vexp : "<< exponent<<'\n'<<"pow : "<< show{bases,std::valarray<int>(exponent, bases.size()), powers2}<<'\n'<<"pow(const value_type& vbase, const std::valarray<T>& exp); (3)\n"<<"vbase: "<< base<<'\n'<<"exp : "<< show{exponents}<<"pow : "<< show{std::valarray<int>(base, bases.size()), exponents, powers3};}
Output:
pow(const std::valarray<T>& base, const std::valarray<T>& exp); (1)base : 1 2 3 4 5 6 7exp : 0 1 2 3 4 5 6pow : 1⁰ 2¹ 3² 4³ 5⁴ 6⁵ 7⁶ = 1 2 9 64 625 7776 117649 pow(const std::valarray<T>& base, const value_type& vexp); (2)base : 1 2 3 4 5 6 7vexp : 5pow : 1⁵ 2⁵ 3⁵ 4⁵ 5⁵ 6⁵ 7⁵ = 1 32 243 1024 3125 7776 16807 pow(const value_type& vbase, const std::valarray<T>& exp); (3)vbase: 2exp : 0 1 2 3 4 5 6pow : 2⁰ 2¹ 2² 2³ 2⁴ 2⁵ 2⁶ = 1 2 4 8 16 32 64
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 3074 | C++98 | T is deduced from both the scalar and thevalarray for(2,3), disallowing mixed-type calls | only deduceT from thevalarray |
| applies the functionstd::sqrt to each element of valarray (function template)[edit] | |
(C++11)(C++11) | raises a number to the given power (\(\small{x^y}\)xy) (function)[edit] |
| complex power, one or both arguments may be a complex number (function template)[edit] |
