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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:
Range Error
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:
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Interface Stability | Standard |
| MT-Level | MT-Safe |
acosh(3M), feclearexcept(3M), fetestexcept(3M), isnan(3M), math.h(3HEAD), matherr(3M), sinh(3M), tanh(3M), attributes(5), standards(5)