Namespaces
Variants

std:: tanh, std:: tanhf, std:: tanhl

From cppreference.net
C++
Numerics library
Common mathematical functions
Nearest integer floating point operations
(C++11)
(C++11)
(C++11) (C++11) (C++11)
Floating point manipulation functions
(C++11) (C++11)
(C++11)
(C++11)
Classification and comparison
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Types
(C++11)
(C++11)
(C++11)
Macro constants
Defined in header <cmath>
(1)
float tanh ( float num ) ;

double tanh ( double num ) ;

long double tanh ( long double num ) ;
(until C++23)
/*floating-point-type*/
tanh ( /*floating-point-type*/ num ) ;
(since C++23)
(constexpr since C++26)
float tanhf ( float num ) ;
(2) (since C++11)
(constexpr since C++26)
long double tanhl ( long double num ) ;
(3) (since C++11)
(constexpr since C++26)
SIMD overload (since C++26)
Defined in header <simd>
template < /*math-floating-point*/ V >

constexpr /*deduced-simd-t*/ < V >

tanh ( const V & v_num ) ;
(S) (since C++26)
Defined in header <cmath>
template < class Integer >
double tanh ( Integer num ) ;
(A) (constexpr since C++26)
1-3) Computes the hyperbolic tangent of num . The library provides overloads of std::tanh for all cv-unqualified floating-point types as the type of the parameter. (since C++23)
S) The SIMD overload performs an element-wise std::tanh on v_num .
(See math-floating-point and deduced-simd-t for their definitions.)
(since C++26)
A) Additional overloads are provided for all integer types, which are treated as double .
(since C++11)

Contents

Parameters

num - floating-point or integer value

Return value

If no errors occur, the hyperbolic tangent of num ( tanh(num) , or
e num
-e -num
e num
+e -num
) is returned.

If a range error occurs due to underflow, the correct result (after rounding) is returned.

Error handling

Errors are reported as specified in math_errhandling .

If the implementation supports IEEE floating-point arithmetic (IEC 60559),

  • if the argument is ±0, ±0 is returned.
  • if the argument is ±∞, ±1 is returned.
  • if the argument is NaN, NaN is returned.

Notes

POSIX specifies that in case of underflow, num is returned unmodified, and if that is not supported, and implementation-defined value no greater than DBL_MIN, FLT_MIN, and LDBL_MIN is returned.

The additional overloads are not required to be provided exactly as (A) . They only need to be sufficient to ensure that for their argument num of integer type, std :: tanh ( num ) has the same effect as std :: tanh ( static_cast < double > ( num ) ) .

Example

Run this code 
#include <cmath>
#include <iostream>
#include <random>
double get_random_between(double min, double max)
{
    std::random_device rd;
    std::mt19937 gen(rd());
    return std::uniform_real_distribution<>(min, max)(gen);
}
int main()
{
    const double x = get_random_between(-1.0, 1.0);
    std::cout << std::showpos
              << "tanh(+1) = " << std::tanh(+1) << '\n'
              << "tanh(-1) = " << std::tanh(-1) << '\n'
              << "tanh(x)*sinh(2*x)-cosh(2*x) = "
              << std::tanh(x) * std::sinh(2 * x) - std::cosh(2 * x) << '\n'
              // special values:
              << "tanh(+0) = " << std::tanh(+0.0) << '\n'
              << "tanh(-0) = " << std::tanh(-0.0) << '\n';
}

Output: 

tanh(+1) = +0.761594
tanh(-1) = -0.761594
tanh(x)*sinh(2*x)-cosh(2*x) = -1
tanh(+0) = +0
tanh(-0) = -0

See also

(C++11) (C++11)
computes hyperbolic sine ( sinh(x) )
(function)
(C++11) (C++11)
computes hyperbolic cosine ( cosh(x) )
(function)
(C++11) (C++11) (C++11)
computes the inverse hyperbolic tangent ( artanh(x) )
(function)
computes hyperbolic tangent of a complex number ( tanh(z) )
(function template)
applies the function std::tanh to each element of valarray
(function template)
C documentation for tanh