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std::log(std::valarray)

From cppreference.com
< cpp‎ | numeric‎ | valarray
 
 
 
 
Defined in header <valarray>
template< class T >
valarray<T> log( const valarray<T>& va );

For each element in va computes natural logarithm of the value of the element.

Contents

[edit] Parameters

va - value array to apply the operation to

[edit] Return value

Value array natural logarithms of the values in va.

[edit] Notes

Unqualified function (log) is used to perform the computation. If such function is not available, std::log 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 a arguments of type const std::valarray& 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> log( const valarray<T>& va )
{
    valarray<T> other = va;
    for (T &i : other) {
        i = log(i);
    }
    return other;
}

[edit] Example

[edit] See also

applies the function std::log10 to each element of valarray
(function template) [edit]
applies the function std::exp to each element of valarray
(function template) [edit]
computes natural (base e) logarithm (to base e) (ln(x))
(function) [edit]
complex natural logarithm with the branch cuts along the negative real axis
(function template) [edit]