Difference between revisions of "cpp/numeric/valarray/tanh"
From cppreference.com
(+= `example`) |
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===Example=== | ===Example=== | ||
| − | {{example | + | {{example | |
| − | |code= | + | | code= |
| − | |output= | + | #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 | ||
}} | }} | ||
Revision as of 14:57, 30 April 2020
| Defined in header <valarray>
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| template< class T > valarray<T> tanh( const valarray<T>& va ); |
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For each element in va computes hyperbolic tangent of the value of the element.
Contents |
Parameters
| va | - | value array to apply the operation to |
Return value
Value array containing hyperbolic tangent of the values in va.
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.
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; } |
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
See also
| applies the function std::sinh to each element of valarray (function template) | |
| applies the function std::cosh to each element of valarray (function template) | |
| (C++11)(C++11) |
computes hyperbolic tangent (tanh(x)) (function) |
| computes hyperbolic tangent of a complex number (tanh(z)) (function template) |
