Defined in header <math.h> | ||
|---|---|---|
float acoshf( float arg ); | (1) | (since C99) |
double acosh( double arg ); | (2) | (since C99) |
long double acoshl( long double arg ); | (3) | (since C99) |
Defined in header <tgmath.h> | ||
#define acosh( arg ) | (4) | (since C99) |
arg.long double, acoshl is called. Otherwise, if the argument has integer type or the type double, acosh is called. Otherwise, acoshf is called. If the argument is complex, then the macro invokes the corresponding complex function (cacoshf, cacosh, cacoshl).| arg | - | floating point value representing the area of a hyperbolic sector |
If no errors occur, the inverse hyperbolic cosine of arg (cosh-1(arg), or arcosh(arg)) on the interval [0, +∞], is returned.
If a domain error occurs, an implementation-defined value is returned (NaN where supported).
Errors are reported as specified in math_errhandling.
If the argument is less than 1, a domain error occurs.
If the implementation supports IEEE floating-point arithmetic (IEC 60559),
FE_INVALID is raised an NaN is returned Although the C standard names this function "arc hyperbolic cosine", the inverse functions of the hyperbolic functions are the area functions. Their argument is the area of a hyperbolic sector, not an arc. The correct name is "inverse hyperbolic cosine" (used by POSIX) or "area hyperbolic cosine".
#include <stdio.h>
#include <math.h>
#include <float.h>
#include <errno.h>
#include <fenv.h>
#pragma STDC FENV_ACCESS ON
int main(void)
{
printf("acosh(1) = %f\nacosh(10) = %f\n", acosh(1), acosh(10));
printf("acosh(DBL_MAX) = %f\nacosh(Inf) = %f\n", acosh(DBL_MAX), acosh(INFINITY));
// error handling
errno = 0; feclearexcept(FE_ALL_EXCEPT);
printf("acosh(0.5) = %f\n", acosh(0.5));
if (errno == EDOM)
perror(" errno == EDOM");
if (fetestexcept(FE_INVALID))
puts(" FE_INVALID raised");
}Possible output:
acosh(1) = 0.000000
acosh(10) = 2.993223
acosh(DBL_MAX) = 710.475860
acosh(Inf) = inf
acosh(0.5) = -nan
errno == EDOM: Numerical argument out of domain
FE_INVALID raised|
(C99)(C99)(C99) | computes inverse hyperbolic sine (\({\small\operatorname{arsinh}{x} }\)arsinh(x)) (function) |
|
(C99)(C99)(C99) | computes inverse hyperbolic tangent (\({\small\operatorname{artanh}{x} }\)artanh(x)) (function) |
|
(C99)(C99) | computes hyperbolic cosine (\({\small\cosh{x} }\)cosh(x)) (function) |
|
(C99)(C99)(C99) | computes the complex arc hyperbolic cosine (function) |
C++ documentation for acosh |
|
| Weisstein, Eric W. "Inverse Hyperbolic Cosine." From MathWorld — A Wolfram Web Resource. |
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