std::log10(std::valarray)
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std::valarray
Defined in header
<valarray>
template< class T >
valarray<T> log10( const valarray<T>& va );
valarray<T> log10( const valarray<T>& va );
For each element in va computes common (base 10) logarithm of the value of the element.
[edit] Parameters
va
-
value array to apply the operation to
[edit] Return value
Value array containing common logarithms of the values in va.
[edit] Notes
Unqualified function (log10) is used to perform the computation. If such function is not available, std::log10 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.
- For every function taking a const std::valarray <T>& except begin() and end() (since C++11), identical functions taking the replacement types shall be added;
- For every function taking two const std::valarray <T>& arguments, identical functions taking every combination of const std::valarray <T>& and replacement types shall be added.
- 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> log10(const valarray<T>& va) { valarray<T> other = va; for (T& i : other) i = log10(i); return other; // proxy object may be returned }
[edit] Example
Run this code
#include <cmath> #include <iomanip> #include <iostream> #include <valarray> void show(char const* title, const std::valarray <float>& va) { std::cout << title << " : " << std::right ; for (float x : va) std::cout << std::setw (6) << x; std::cout << '\n'; } int main() { const std::valarray <float> n{-2.f, -1.f, 0.f, 1.f, 2.f, 3.f, INFINITY }; const std::valarray <float> pow10{std::pow (10.f, n)}; const std::valarray <float> log10_pow10{std::log10 (pow10)}; show("n ", n); show("10n ", pow10); show("lg(10n)", log10_pow10); }
Output:
n : -2 -1 0 1 2 3 inf 10n : 0.01 0.1 1 10 100 1000 inf lg(10n) : -2 -1 0 1 2 3 inf
[edit] See also
(C++11)(C++11)
(function) [edit]
complex common logarithm with the branch cuts along the negative real axis
(function template) [edit]
(function template) [edit]
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