Hyperbolic Functions

The functions in this section are related to the exponential functions; see section Exponentiation and Logarithms.

Function: double sinh (double x)
The `sinh` function returns the hyperbolic sine of x, defined mathematically as `exp (x) - exp (-x) / 2`. The function fails, and sets `errno` to `ERANGE`, if the value of x is too large; that is, if overflow occurs.

Function: double cosh (double x)
The `cosh` function returns the hyperbolic cosine of x, defined mathematically as `exp (x) + exp (-x) / 2`. The function fails, and sets `errno` to `ERANGE`, if the value of x is too large; that is, if overflow occurs.

Function: double tanh (double x)
This function returns the hyperbolic tangent of x, whose mathematical definition is `sinh (x) / cosh (x)`.

Function: double asinh (double x)
This function returns the inverse hyperbolic sine of x---the value whose hyperbolic sine is x.

Function: double acosh (double x)
This function returns the inverse hyperbolic cosine of x---the value whose hyperbolic cosine is x. If x is less than `1`, `acosh` returns `HUGE_VAL`.

Function: double atanh (double x)
This function returns the inverse hyperbolic tangent of x---the value whose hyperbolic tangent is x. If the absolute value of x is greater than or equal to `1`, `atanh` returns `HUGE_VAL`.