atanh, atanhf, atanhl

Calculates the inverse hyperbolic tangent.

double atanh(
   double x 
);
float atanh(
   float x 
);  // C++ only
long double atanh(
   long double x
);  // C++ only
float atanhf(
   float x 
);
long double atanhl(
   long double x
);

Parameters

  • x
    Floating-point value.

Return Value

The atanh functions return the inverse hyberbolic tangent (arc hyperbolic tangent) of x. If x is greater than 1, or less than –1, errno is set to EDOM and the result is a quiet NaN. If x is equal to 1 or -1, a positive or negative infinity is returned, respectively, and errno is set to ERANGE.

Input

SEH Exception

Matherr Exception

± QNAN,IND

none

none

X ≥ 1; x ≤ -1

none

none

Remarks

Because C++ allows overloading, you can call overloads of atanh that take and return float or long double values. In a C program, atanh always takes and returns double.

Requirements

Function

C header

C++ header

atanh, atanhf, atanhl

<math.h>

<cmath>

For additional compatibility information, see Compatibility.

Example

// crt_atanh.c
// This program displays the hyperbolic tangent of pi / 4
// and the arc hyperbolic tangent of the result.
//

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

int main( void )
{
   double pi = 3.1415926535;
   double x, y;

   x = tanh( pi / 4 );
   y = atanh( x );
   printf( "tanh( %f ) = %f\n", pi/4, x );
   printf( "atanh( %f ) = %f\n", x, y );
}
tanh( 0.785398 ) = 0.655794
atanh( 0.655794 ) = 0.785398

.NET Framework Equivalent

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

See Also

Reference

Floating-Point Support

Long Double

acos, acosf, acosl

asin, asinf, asinl

atan, atanf, atanl, atan2, atan2f, atan2l

cos, cosf, cosl, cosh, coshf, coshl

sin, sinf, sinl, sinh, sinhf, sinhl

tan, tanf, tanl, tanh, tanhf, tanhl

_CItan