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

Parameters

Return value

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

#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';
}

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