Mathematical Library Functions                          acosh(3M)



NAME
     acosh, acoshf, acoshl - inverse hyperbolic cosine functions

SYNOPSIS
     c99 [ flag... ] file... -lm [ library... ]
     #include 

     double acosh(double x);


     float acoshf(float x);


     long double acoshl(long double x);


DESCRIPTION
     These functions compute the  inverse  hyperbolic  cosine  of
     their argument x.

RETURN VALUES
     Upon  successful  completion,  these  functions  return  the
     inverse hyperbolic cosine of their argument.


     For finite values of  x < 1, a domain error occurs  and  NaN
     is returned.


     If x is NaN, NaN is returned.


     If x is ]1, ]0 is returned.


     If x is ]Inf, ]Inf is returned.


     If x is -Inf, a domain error occurs and NaN is returned.


     For exceptional cases, matherr(3M) tabulates the  values  to
     be returned by acosh() as specified by SVID3 and XPG3.

ERORS
     These functions will fail if:

     Domain Error    The x argument is finite and less than  1.0,
                     or is -Inf.

                     If the integer expression  (matherrhandling
                     &  MATHEREXCEPT)  is non-zero, the invalid



SunOS 5.11          Last change: 12 Jul 2006                    1






Mathematical Library Functions                          acosh(3M)



                     floating-point exception is raised.

                     The acosh() function sets errno to EDOM if x
                     is less than 1.0.


USAGE
     An application wanting to check for exceptions  should  call
     feclearexcept(FEALEXCEPT) before calling these functions.
     On  return,  if  fetestexcept(FEINVALID    FEDIVBYZERO  
     FEOVERFLOW    FEUNDERFLOW)  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
     acosh().  On  return,  if  errno  is  non-zero, an error has
     occurred. The acoshf() and acoshl()  functions  do  not  set
     errno.

ATRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:



     
           ATRIBUTE TYPE               ATRIBUTE VALUE       
    
     Interface Stability          Standard                    
    
     MT-Level                     MT-Safe                     
    


SEE ALSO
     cosh(3M),        feclearexcept(3M),        fetestexcept(3M),
     math.h(3HEAD), matherr(3M), attributes(5), standards(5)
















SunOS 5.11          Last change: 12 Jul 2006                    2