Hyperbolic tangent function
#include <math.h> double tanh(double x); float tanhf(float x); long double tanhl(long double x);
Link with -lm.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or cc -std=c99
The tanh() function returns the hyperbolic tangent of x, which is defined mathematically as:
tanh(x) = sinh(x) / cosh(x)
On success, these functions return the hyperbolic tangent of x.
If x is a NaN, a NaN is returned.
If x is +0 (-0), +0 (-0) is returned.
If x is positive infinity (negative infinity), +1 (-1) is returned.
No errors occur.
The tanh(), tanhf(), and tanhl() functions are thread-safe.
C99, POSIX.1-2001. The variant returning double also conforms to SVr4, 4.3BSD, C89.
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