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std::acos(std::valarray)

From cppreference.com
< cpp‎ | numeric‎ | valarray
 
 
Numerics library
 
std::valarray
 
Defined in header <valarray>
template< class T >
valarray<T> acos( const valarray<T>& va );

For each element in va computes arc cosine of the value of the element.

[edit] Parameters

va - value array to apply the operation to

[edit] Return value

Value array containing arc cosines of the values in va.

[edit] Notes

Unqualified function (acos) is used to perform the computation. If such function is not available, std::acos is used due to argument-dependent lookup.

The function can be implemented with the return type different from std::valarray . In this case, the replacement type has the following properties:

[edit] Possible implementation

template<class T>
valarray<T> acos(const valarray<T>& va)
{
 valarray<T> other = va;
 for (T& i : other)
 i = acos(i);
 
 return other; // proxy object may be returned
}

[edit] Example

Run this code
#include <cmath>
#include <iostream>
#include <numbers>
#include <valarray>
 
int main()
{
 // take common x-values from unit circle
 const double s32 = std::sqrt (3.0) / 2.0;
 const double s22 = std::sqrt (2.0) / 2.0;
 std::valarray <double> v1 = {-1.0, -s32, -s22, -0.5, 0.0, 0.5, s22, s32, 1.0};
 std::valarray <double> v2 = std::acos (v1) * 180.0 / std::numbers::pi ;
 
 for (double n : v2)
 std::cout << n << "° ";
 std::cout << '\n';
}

Output:

180° 150° 135° 120° 90° 60° 45° 30° 0°

[edit] See also

applies the function std::asin to each element of valarray
(function template) [edit]
applies the function std::atan to each element of valarray
(function template) [edit]
applies the function std::atan2 to a valarray and a value
(function template) [edit]
applies the function std::cos to each element of valarray
(function template) [edit]
(C++11)(C++11)
computes arc cosine (\({\small\arccos{x}}\)arccos(x))
(function) [edit]
computes arc cosine of a complex number (\({\small\arccos{z}}\)arccos(z))
(function template) [edit]
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