< cpp‎ | numeric‎ | valarray
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.


[edit] Parameters

va - value array to apply the operation to

[edit] Return value

Value array containing arc sines of the values in va.

[edit] 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:

[edit] 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;

[edit] Example

#include <cmath>
#include <iostream>
#include <valarray>
const double pi = 4.0 * atan(1.0);
int main()
    // take common y-values from unit circle
    std::valarray<double> v1 = {-1.0, -sqrt(3.0)/2.0, -sqrt(2.0)/2.0, -0.5, 0.0, 0.5, sqrt(2.0)/2.0, sqrt(3.0)/2.0, 1.0};
    std::valarray<double> v2 = std::asin(v1) * 180.0 / pi;;
    for(double n : v2)
        std::cout << std::fixed << n << ' ';
    std::cout << '\n';


-90.000000 -60.000000 -45.000000 -30.000000 0.000000 30.000000 45.000000 60.000000 90.000000

[edit] See also

applies the function std::acos 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::sin to each element of valarray
(function template) [edit]
computes arc sine (arcsin(x))
(function) [edit]
computes arc sine of a complex number (arcsin(z))
(function template) [edit]