acosh, acoshf, acoshl - cppreference.com (original) (raw)

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)

1-3) Computes the inverse hyperbolic cosine of arg.

  1. Type-generic macro: If the argument has type 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).

Contents

[edit] Parameters

arg - floating-point value representing the area of a hyperbolic sector

[edit] Return value

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).

[edit] Error handling

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),

[edit] Notes

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".

[edit] Example

#include <errno.h> #include <fenv.h> #include <float.h> #include <math.h> #include <stdio.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

[edit] References

[edit] See also