Synopsis
#include <math.h>
double tanh(double x);
float tanhf(float x);
long double tanhl(long double x);
Status
Partially implemented
Conformance
IEEE Std 1003.1-2017
Description
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.
Errors
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.
Tests
Untested
Known bugs
None