NAME¶

std::asin(std::valarray) - std::asin(std::valarray)

Synopsis¶

Defined in header <valarray>
template< class T >
valarray<T> asin( const valarray<T>& va );

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

Parameters¶

va - value array to apply the operation to

Return value¶

Value array containing arc sines of the values in va.

Notes¶

Unqualified function (asin) is used to perform the computation. If such function is
not available, std::asin 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:

* All const member functions of std::valarray are provided.
* std::valarray, std::slice_array, std::gslice_array, std::mask_array and
std::indirect_array can be constructed from the replacement type.
* All functions accepting an argument of type const std::valarray&
except begin() and end()
(since C++11) should also accept the replacement type.
* All functions accepting two arguments of type const std::valarray&
should accept every combination of const std::valarray& and the
replacement type.
* The return type does not add more than two levels of template nesting
over the most deeply-nested argument type.

Possible implementation¶

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

Example¶

// Run this code

#include <cmath>
#include <numbers>
#include <iostream>
#include <valarray>

int main()
{
// take common y-values from unit circle
const double s22 = std::sqrt(2.0) / 2.0;
const double s32 = std::sqrt(3.0) / 2.0;
const std::valarray<double> v1 =
{-1.0, -s32, -s22, -0.5, 0.0, 0.5, s22, s32, 1.0};

// fill with results of radians to degrees conversion
const std::valarray<double> v2 =
std::asin(v1) * 180.0 / std::numbers::pi;

for(std::cout << std::showpos; double n : v2)
std::cout << n << "° ";
std::cout << '\n';
}

Output:¶

-90° -60° -45° -30° +0° +30° +45° +60° +90°

See also¶

acos(std::valarray) applies the function std::acos to each element of valarray
(function template)
atan(std::valarray) applies the function std::atan to each element of valarray
(function template)
atan2(std::valarray) applies the function std::atan2 to a valarray and a value
(function template)
sin(std::valarray) applies the function std::sin to each element of valarray
(function template)
asin
asinf computes arc sine (\({\small\arcsin{x} }\)arcsin(x))
asinl (function)
(C++11)
(C++11)
asin(std::complex) computes arc sine of a complex number (\({\small\arcsin{z}
(C++11) }\)arcsin(z))
(function template)