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Manual Reference Pages  - ACOSH (3)

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acosh, acoshf, acoshl - inverse hyperbolic cosine function

CONTENTS

Synopsis
Description
Errors

#include <math.h> 



double acosh(double x); 



float acoshf(float x); 



long double acoshl(long double x); 

The acosh() function calculates the inverse hyperbolic cosine of x; that is the value whose hyperbolic cosine is x. If x is less than 1.0, acosh() returns not-a-number (NaN) and errno is set.

EDOM	x is out of range.

SVID 3, POSIX, BSD 4.3, ISO 9899. The float and long double variants are C99 requirements.

asinh(3), atanh(3), cosh(3), sinh(3), tanh(3)

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