acosh(), acoshf(), acoshl()

Compute the inverse hyperbolic cosine

Synopsis:

#include <math.h>

double acosh( double x );

float acoshf( float x );

long double acoshl( long double x );

Arguments:

x
The value for which you want to compute the inverse hyperbolic cosine.

Library:

libm

Use the -l m option to qcc to link against this library.

Description:

These functions compute the inverse hyperbolic cosine (in radians) of x.

To check for error situations, use feclearexcept() and fetestexcept():

Returns:

The inverse hyperbolic cosine (in radians) of x.

If x is: These functions return:
< 1 and finite NaN, and a domain error occurs
NaN NaN
1 0
+Inf +Inf
-Inf NaN, and a domain error occurs

Errors:

FE_INVALID
The x argument is finite and less than 1, or is -Inf.

Examples:

#include <stdio.h>
#include <math.h>
#include <fenv.h>
#include <stdlib.h>

int main( void )
{
    int except_flags;

    feclearexcept(FE_ALL_EXCEPT);

    printf( "%f\n", acosh( 1.5 ) );

    except_flags = fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW);
    if(except_flags) {
        /* An error occurred; handle it appropriately. */
    }

    return EXIT_SUCCESS;
}

produces the output:

0.962424

Classification:

ANSI, POSIX 1003.1

Safety:  
Cancellation point No
Interrupt handler No
Signal handler No
Thread Yes