# std::tanh

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< cpp‎ | numeric‎ | math

Defined in header `<cmath>` |  |
float tanh( float arg ); | (1) |
double tanh( double arg ); | (2) |
long double tanh( long double arg ); | (3) |
double tanh( Integral arg ); | (4) | (since C++11)

Computes the hyperbolic tangent of `arg`

4) A set of overloads or a function template accepting an argument of any integral type. Equivalent to 2) (the argument is cast to double).

### Parameters

arg | - | value of a floating-point or Integral type

### Return value

If no errors occur, the hyperbolic tangent of `arg` (tanh(arg), or

earg -e-arg
earg +e-arg

) 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, `arg` 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.

### Examples

Run this code

    #include <iostream>
    #include <cmath>

    int main()
    {
        std::cout << "tanh(1) = " << std::tanh(1) << '\n'
                  << "tanh(-1) = " << std::tanh(-1) << '\n'
                  << "tanh(0.1)*sinh(0.2)-cosh(0.2) = "
                  << std::tanh(0.1) * std::sinh(0.2) - std::cosh(0.2) << '\n';
        // special values
        std::cout << "tanh(+0) = " << std::tanh(+0.0) << '\n'
                  << "tanh(-0) = " <<  std::tanh(-0.0) << '\n';
    }

Output:

    tanh(1) = 0.761594
    tanh(-1) = -0.761594
    tanh(0.1)*sinh(0.2)-cosh(0.2) = -1
    tanh(+0) = 0
    tanh(-0) = -0

### See also

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

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