acosh, acoshf, acoshl

Article
06/05/2017

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The latest version of this topic can be found at acosh, acoshf, acoshl.

Calculates the inverse hyperbolic cosine.

Syntax

double acosh(  
   double x   
);  
float acosh(  
   float x   
);  // C++ only  
long double acosh(  
   long double x  
);  // C++ only  
float acoshf(  
   float x   
);  
long double acoshl(  
   long double x  
);

Parameters

x
Floating-point value.

Return Value

The acosh functions return the inverse hyberbolic cosine (arc hyperbolic cosine) of x. These functions are valid over the domain x ≥ 1. If x is less than 1, errno is set to EDOM and the result is a quiet NaN. If x is a quiet NaN, indefinite, or infinity, the same value is returned.

Input	SEH Exception	`_matherr` Exception
± QNAN, IND, INF	none	none
x < 1	none	none

Remarks

When you use C++, you can call overloads of acosh that take and return float or long double values. In a C program, acosh always takes and returns double.

Requirements

Function	C header	C++ header
`acosh`, `acoshf`, `acoshl`	<math.h>	<cmath>

For additional compatibility information, see Compatibility.

Example

// crt_acosh.c  
// Compile by using: cl /W4 crt_acosh.c  
// This program displays the hyperbolic cosine of pi / 4  
// and the arc hyperbolic cosine of the result.  
  
#include <math.h>  
#include <stdio.h>  
  
int main( void )  
{  
   double pi = 3.1415926535;  
   double x, y;  
  
   x = cosh( pi / 4 );  
   y = acosh( x );  
   printf( "cosh( %f ) = %f\n", pi/4, x );  
   printf( "acosh( %f ) = %f\n", x, y );  
}

cosh
( 0.785398 ) = 1.324609  
acosh
( 1.324609 ) = 0.785398

.NET Framework Equivalent

Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.