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std::tanh(std::valarray)

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

For each element in va computes hyperbolic tangent of the value of the element.

Contents

[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:

[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;
}

[edit] Example

#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

applies the function std::sinh to each element of valarray
(function template) [edit]
applies the function std::cosh to each element of valarray
(function template) [edit]
(C++11)(C++11)
computes hyperbolic tangent (tanh(x))
(function) [edit]
computes hyperbolic tangent of a complex number (tanh(z))
(function template) [edit]