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Difference between revisions of "cpp/numeric/valarray/acos"

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< cpp‎ | numeric‎ | valarray
m (Text replace - "===Equivalent function===" to "===Possible implementation===")
m (fmt, {{c}}, headers sorted, langlinks)
 
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{{cpp/title|acos{{small|(std::valarray)}}}}
 
{{cpp/title|acos{{small|(std::valarray)}}}}
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{{cpp/numeric/valarray/sidebar}}
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{{cpp/numeric/valarray/navbar}}
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{{ddcl | header=valarray | 1=
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{{ddcl|header=valarray|1=
 
template< class T >
 
template< class T >
 
valarray<T> acos( const valarray<T>& va );
 
valarray<T> acos( const valarray<T>& va );
 
}}
 
}}
  
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For each element in {{tt|va}} computes arc cosine of the value of the element. This is done by applying {{cpp|acos}} (unqualified) function.  
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For each element in {{c|va}} computes arc cosine of the value of the element.
  
 
===Parameters===
 
===Parameters===
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{{param list begin}}
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{{par begin}}
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{{param list item | va | value array to apply the operation to}}
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{{par|va|value array to apply the operation to}}
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{{param list end}}
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{{par end}}
  
 
===Return value===
 
===Return value===
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Value array containing arc cosines of the values in {{tt|va}}.
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Value array containing arc cosines of the values in {{c|va}}.
  
 
===Notes===
 
===Notes===
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{{cpp/numeric/valarray/notes|acos}}
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{{cpp/numeric/valarray/notes unq|acos}}
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 +
{{cpp/numeric/valarray/notes ret|acos}}
  
 
===Possible implementation===
 
===Possible implementation===
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{{eq fun cpp | 1=
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{{cpp/numeric/valarray/impl|acos}}
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template< class T >
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valarray<T> acos( const valarray<T>& va )
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{
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    valarray<T> other = va;
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    for (T &i : other) {
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        i = acos(i);
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    }
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}
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}}
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===Example===
 
===Example===
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{{example cpp
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{{example
 
|code=
 
|code=
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|output=
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#include <cmath>
 +
#include <iostream>
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#include <numbers>
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#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 << "° ";
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    std::cout << '\n';
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}
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|output=180° 150° 135° 120° 90° 60° 45° 30° 0°
 
}}
 
}}
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 +
===See also===
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{{dsc begin}}
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{{dsc inc|cpp/numeric/valarray/dsc asin}}
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{{dsc inc|cpp/numeric/valarray/dsc atan}}
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{{dsc inc|cpp/numeric/valarray/dsc atan2}}
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{{dsc inc|cpp/numeric/valarray/dsc cos}}
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{{dsc inc|cpp/numeric/math/dsc acos}}
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{{dsc inc|cpp/numeric/complex/dsc acos}}
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{{dsc end}}
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 +
{{langlinks|de|es|fr|it|ja|pt|ru|zh}}

Latest revision as of 00:09, 17 October 2023

 
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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.

Contents

[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 (arccos(x))
(function) [edit]
(C++11)
 computes arc cosine of a complex number (arccos(z))
(function template) [edit]
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