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# std::acos(std::valarray)

From cppreference.com
< cpp‎ | numeric‎ | 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:

  - 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++14) 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.

### [edit] Possible implementation

    template<class T>
    valarray<T> acos(const valarray<T>& va)
    {
        valarray<T> other = va;
        for (T &i : other) {
            i = acos(i);
        }
    }

### [edit] Example

| This section is incomplete Reason: no example

### [edit] See also

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

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- Todo no example