1ACOSH(P)                   POSIX Programmer's Manual                  ACOSH(P)
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NAME

6       acosh, acoshf, acoshl - inverse hyperbolic cosine functions
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SYNOPSIS

9       #include <math.h>
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11       double acosh(double x);
12       float acoshf(float x);
13       long double acoshl(long double x);
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DESCRIPTION

17       These  functions  shall  compute the inverse hyperbolic cosine of their
18       argument x.
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20       An application wishing to check for error situations should  set  errno
21       to  zero  and  call  feclearexcept(FE_ALL_EXCEPT)  before calling these
22       functions.  On return, if errno is non-zero or  fetestexcept(FE_INVALID
23       |  FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has
24       occurred.
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RETURN VALUE

27       Upon successful completion, these functions shall  return  the  inverse
28       hyperbolic cosine of their argument.
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30       For  finite  values of x < 1, a domain error shall occur, and  either a
31       NaN (if supported),  or    an  implementation-defined  value  shall  be
32       returned.
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34       If x is NaN, a NaN shall be returned.
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36       If x is +1, +0 shall be returned.
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38       If x is +Inf, +Inf shall be returned.
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40       If  x  is  -Inf,  a domain error shall occur, and either a NaN (if sup‐
41       ported), or an implementation-defined value shall be returned.
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ERRORS

44       These functions shall fail if:
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46       Domain Error
47              The x argument is finite and less than +1.0,    or is -Inf.
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49       If the integer expression (math_errhandling & MATH_ERRNO) is  non-zero,
50       then   errno  shall  be  set  to  [EDOM].  If  the  integer  expression
51       (math_errhandling &  MATH_ERREXCEPT)  is  non-zero,  then  the  invalid
52       floating-point exception shall be raised.
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55       The following sections are informative.
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EXAMPLES

58       None.
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APPLICATION USAGE

61       On   error,   the   expressions  (math_errhandling  &  MATH_ERRNO)  and
62       (math_errhandling & MATH_ERREXCEPT) are independent of each other,  but
63       at least one of them must be non-zero.
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RATIONALE

66       None.
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FUTURE DIRECTIONS

69       None.
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SEE ALSO

72       cosh() , feclearexcept() , fetestexcept() , the Base Definitions volume
73       of IEEE Std 1003.1-2001, Section 4.18, Treatment  of  Error  Conditions
74       for Mathematical Functions, <math.h>
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77       Portions  of  this text are reprinted and reproduced in electronic form
78       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
79       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
80       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
81       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
82       event of any discrepancy between this version and the original IEEE and
83       The  Open Group Standard, the original IEEE and The Open Group Standard
84       is the referee document. The original Standard can be  obtained  online
85       at http://www.opengroup.org/unix/online.html .
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89IEEE/The Open Group                  2003                             ACOSH(P)
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