The ACOSH() function calculates the inverse hyperbolic cosine of x. That is the value whose hyperbolic cosine is x. If x is less than 1.0, acosh() returns not-a-number (NaN) and errno is set.
De funksje ACOSH( x) berekkent de ynverze hyperbolysk kosinus y fan x; dit is de wearde wêrfan de hyperbolyske kosinus x is. (x út [1, - >), y > =0 (per definysje)). As x lytser is as 1, 0, dan jout ACOSH () "not- a- number" (nan) en is der in foutmelding. De oare wearde fan y dy' t foldocht oan COSH( y) =x is - y.