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atanh, atanhf : inverse hyperbolic tangent

Synopsis

Section titled “Synopsis”
#include <math.h>
double atanh(double x);
float atanhf(float x);
```### Description


atanh calculates the inverse hyperbolic tangent of x. atanhf is identical, other than taking and returning float values.### Returns


atanh and atanhf return the calculated value. If is greater than 1, the global errno is set to EDOM and the result is a NaN. A DOMAIN error is reported. If is 1, the global errno is set to EDOM; and the result is infinity with the same sign as x. A SING error is reported. You can modify the error handling for these routines using matherr.


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**Authoritative source**: BUSMASTER DITA help source `atanh.dita`, compiled into `BUSMASTER.CHM` with the application.