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HP-UX 11i Version 3: February 2007

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acosh(), acoshf(), acoshl(), acoshw(), acoshq() — arc hyperbolic cosine functions


#include <math.h>

double acosh(double x);

HP Integrity Server Only

float acoshf(float x);

long double acoshl(long double x);

extended acoshw(extended x);

quad acoshq(quad x);


acosh() returns the arc hyperbolic cosine of x, in the range +zero to +INFINITY.

Integrity Server Only

acoshf() is a float version of acosh(); it takes a float argument and returns a float result.

acoshl() is a long double version of acosh(); it takes a long double argument and returns a long double result.

acoshw() is an extended version of acosh(); it takes an extended argument and returns an extended result.

acoshq() is equivalent to acoshl() on HP-UX systems.


To use (for Integrity servers) acoshf(), acoshl(), acoshw(), or acoshq(), compile either with the default -Ae option or with the -Aa and -D_HPUX_SOURCE options.

To use (for Integrity servers) acoshw() or acoshq(), compile also with the -fpwidetypes option.

To use any of these functions, make sure your program includes <math.h>, and link in the math library by specifying -lm on the compiler or linker command line.

For more information, see the HP-UX floating-point guide for HP Integrity servers at the following site: http://www.hp.com/go/fp.


acosh() returns +0.

If x < 1.0, acosh() returns NaN and raises the invalid exception.

If x is +INFINITY, acosh() returns +INFINITY.

If x is NaN, acosh() returns NaN.

When it raises no other exception, whether acosh() raises the inexact exception is unspecified.


If x < 1.0, acosh() sets errno to [EDOM].

Integrity Server Only

HPUX libm functions on Integrity servers do not set errno by default. For errno setting, compile with the +Olibmerrno option.


acosh(), acoshf(), acoshl() : ISO/IEC C99 (including Annex F, ``IEC 60559 floating-point arithmetic'')

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