|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Defined in header <math.h> | ||
float atanhf(float arg); | (1) | (since C99) |
double atanh(double arg); | (2) | (since C99) |
longdouble atanhl(longdouble arg); | (3) | (since C99) |
Defined in header <tgmath.h> | ||
#define atanh( arg ) | (4) | (since C99) |
atanhl is called. Otherwise, if the argument has integer type or the typedouble,atanh is called. Otherwise,atanhf is called. If the argument is complex, then the macro invokes the corresponding complex function (catanhf,catanh,catanhl).Contents |
| arg | - | floating_point value representing the area of a hyperbolic sector |
If no errors occur, the inverse hyperbolic tangent ofarg (tanh-1
(arg), orartanh(arg)), is returned.
If a domain error occurs, an implementation-defined value is returned (NaN where supported).
If a pole error occurs,±HUGE_VAL,±HUGE_VALF, or±HUGE_VALL is returned (with the correct sign).
If a range error occurs due to underflow, the correct result (after rounding) is returned.
Errors are reported as specified inmath_errhandling.
If the argument is not on the interval[-1, +1], a range error occurs.
If the argument is ±1, a pole error occurs.
If the implementation supports IEEE floating-point arithmetic (IEC 60559),
Although the C standard names this function "arc hyperbolic tangent", 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 tangent" (used by POSIX) or "area hyperbolic tangent".
POSIX specifies that in case of underflow,arg is returned unmodified, and if that is not supported, an implementation-defined value no greater thanDBL_MIN,FLT_MIN, andLDBL_MIN is returned.
#include <errno.h>#include <fenv.h>#include <float.h>#include <math.h>#include <stdio.h>// #pragma STDC FENV_ACCESS ON int main(void){printf("atanh(0) = %f\natanh(-0) = %f\n", atanh(0), atanh(-0.0));printf("atanh(0.9) = %f\n", atanh(0.9)); // error handlingerrno=0;feclearexcept(FE_ALL_EXCEPT);printf("atanh(-1) = %f\n", atanh(-1));if(errno==ERANGE)perror(" errno == ERANGE");if(fetestexcept(FE_DIVBYZERO))puts(" FE_DIVBYZERO raised");}
Possible output:
atanh(0) = 0.000000atanh(-0) = -0.000000atanh(0.9) = 1.472219atanh(-1) = -inf errno == ERANGE: Numerical result out of range FE_DIVBYZERO raised
(C99)(C99)(C99) | computes inverse hyperbolic sine (\({\small\operatorname{arsinh}{x} }\)arsinh(x)) (function)[edit] |
(C99)(C99)(C99) | computes inverse hyperbolic cosine (\({\small\operatorname{arcosh}{x} }\)arcosh(x)) (function)[edit] |
(C99)(C99) | computes hyperbolic tangent (\({\small\tanh{x} }\)tanh(x)) (function)[edit] |
(C99)(C99)(C99) | computes the complex arc hyperbolic tangent (function)[edit] |
C++ documentation foratanh | |
| Weisstein, Eric W. "Inverse Hyperbolic Tangent." From MathWorld — A Wolfram Web Resource. |
