- hyperbolic cosine function
c99 [ flag... ] file... -lm [ library... ] #include <math.h> double cosh(double x);
float coshf(float x);
long double coshl(long double x);
These functions compute the hyperbolic cosine of their argument x.
Upon successful completion, these functions return the hyperbolic cosine of x.
If the correct value would cause overflow, a range error occurs and cosh(), coshf(), and coshl() return the value of the macro HUGE_VAL, HUGE_VALF, and HUGE_VALL, respectively.
If x is NaN, a NaN is returned.
If x is ±0, 1.0 is returned.
If x is ±Inf, ±Inf is returned.
For exceptional cases, matherr(3M) tabulates the values to be returned by cosh() as specified by SVID3 and XPG3.
These functions will fail if:
The result would cause an overflow.
If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, the overflow floating-point exception is raised.
The cosh() function sets errno to ERANGE if the result would cause an overflow.
An application wanting to check for exceptions should call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an exception has been raised. An application should either examine the return value or check the floating point exception flags to detect exceptions.
An application can also set errno to 0 before calling cosh(). On return, if errno is non-zero, an error has occurred. The coshf() and coshl() functions do not set errno.
See attributes(5) for descriptions of the following attributes: