std::log(std::valarray) (3) - Linux Manuals

std::log(std::valarray): std::log(std::valarray)


std::log(std::valarray) - std::log(std::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.


va - value array to apply the operation to

Return value

Value array containing natural logarithms of the values in va.


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 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> log( const valarray<T>& va )
      valarray<T> other = va;
      for (T &i : other) {
          i = log(i);
      return other;


 This section is incomplete
 Reason: no example

See also

                     applies the function std::log10 to each element of valarray
log10(std::valarray) (function template)
                     applies the function std::exp to each element of valarray
exp(std::valarray) (function template)

logl computes natural (base e) logarithm (ln(x))

                     complex natural logarithm with the branch cuts along the negative real axis
log(std::complex) (function template)