acosh
, acoshf
—inverse hyperbolic cosine#include <math.h> double acosh(double x); float acoshf(float x);
Description
acosh
calculates the inverse hyperbolic cosine of x.
acosh
is defined as
log(x + sqrt(x*x-1))
x must be a number greater than or equal to 1.
acoshf
is identical, other than taking and returning floats.
Returns
acosh
and acoshf
return the calculated value. If x
less than 1, the return value is NaN and errno
is set to EDOM
.
You can change the error-handling behavior with the non-ANSI
matherr
function.
Portability
acosh
nor acoshf
are ANSI C. They are not recommended
for portable programs.