#include <math.h>

double tanh(double x);

float tanhf(float x);

long double tanhl(long double x);


Partially implemented


IEEE Std 1003.1-2017


These functions shall compute the hyperbolic tangent of their argument x.

An application wishing to check for error situations should set errno to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if errno is non-zero or fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.

Return value#

Upon successful completion, these functions shall return the hyperbolic tangent of x.

If x is NaN, a NaN shall be returned.

If x is ±0, x shall be returned.

If x is ±Inf, ±1 shall be returned.

If x is subnormal, a range error may occur and x should be returned.

If x is not returned, tanh(), tanhf(), and tanhl() shall return an implementation-defined value no greater in magnitude than DBL_MIN, FLT_MIN, and LDBL_MIN, respectively.


These functions may fail if:

  • ERANGE - The value of x is subnormal.

If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to ERANGE. If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the underflow floating-point exception shall be raised.



Known bugs#


See Also#

  1. Standard library functions

  2. Table of Contents