std::acosh
From cppreference.com
                    
                                        
                    
                    
                                                            
                    |   Defined in header <cmath>
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|   float       acosh( float arg );  | 
(since C++11) | |
|   double      acosh( double arg );  | 
(since C++11) | |
|   long double acosh( long double arg );  | 
(since C++11) | |
|   double      acosh( Integral arg );  | 
(since C++11) | |
Computes hyperbolic arc cosine of arg
Contents | 
[edit] Parameters
| arg | - | floating point value | 
[edit] Return value
inverse hyperbolic cosine of arg
[edit] See also
|    (C++11)  | 
  hyperbolic arc sine   (function)  | 
|    (C++11)  | 
  hyperbolic arc tangent   (function)  | 
|   computes hyperbolic cosine (ch(x))  (function)  | |
|    (C++11)  | 
   computes hyperbolic arc cosine of a complex number   (function template)  | 
[edit] External links
Weisstein, Eric W. "Inverse Hyperbolic Cosine." From MathWorld--A Wolfram Web Resource.