std::tanh(std::valarray)
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std::valarray
Defined in header
<valarray>
template< class T >
valarray<T> tanh( const valarray<T>& va );
valarray<T> tanh( const valarray<T>& va );
For each element in va computes hyperbolic tangent of the value of the element.
[edit] Parameters
va
-
value array to apply the operation to
[edit] Return value
Value array containing hyperbolic tangent of the values in va.
[edit] Notes
Unqualified function (tanh) is used to perform the computation. If such function is not available, std::tanh 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> tanh(const valarray<T>& va) { valarray<T> other = va; for (T& i : other) i = tanh(i); return other; // proxy object may be returned }
[edit] Example
Run this code
#include <cmath> #include <iostream> #include <valarray> auto show = [](char const* title, const std::valarray <double>& va) { std::cout << title << " :"; for (auto x : va) std::cout << " " << std::fixed << x; std::cout << '\n'; }; int main() { const std::valarray <double> x = {.0, .1, .2, .3}; const std::valarray <double> sinh = std::sinh (x); const std::valarray <double> cosh = std::cosh (x); const std::valarray <double> tanh = std::tanh (x); const std::valarray <double> tanh_by_def = sinh / cosh; const std::valarray <double> tanh_2x = std::tanh (2.0 * x); const std::valarray <double> tanh_2x_by_def = (2.0 * tanh) / (1.0 + std::pow (tanh, 2.0)); show("x ", x); show("tanh(x) ", tanh); show("tanh(x) (def) ", tanh_by_def); show("tanh(2*x) ", tanh_2x); show("tanh(2*x) (def)", tanh_2x_by_def); }
Output:
x : 0.000000 0.100000 0.200000 0.300000 tanh(x) : 0.000000 0.099668 0.197375 0.291313 tanh(x) (def) : 0.000000 0.099668 0.197375 0.291313 tanh(2*x) : 0.000000 0.197375 0.379949 0.537050 tanh(2*x) (def) : 0.000000 0.197375 0.379949 0.537050
[edit] See also
computes hyperbolic tangent of a complex number (\({\small\tanh{z}}\)tanh(z))
(function template) [edit]
(function template) [edit]
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