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

Defined in header <cmath>
float       tanh ( float arg );
float       tanhf( float arg );
(since C++11)
double      tanh ( double arg );
long double tanh ( long double arg );
long double tanhl( long double arg );
(since C++11)
double      tanh ( IntegralType arg );
(4) (since C++11)
1-3) 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).


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


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.


#include <iostream>
#include <cmath>
int main()
    std::cout << std::showpos
              << "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:
              << "tanh(+0) = " << std::tanh(+0.0) << '\n'
              << "tanh(-0) = " << std::tanh(-0.0) << '\n';


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

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

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