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.\" from: @(#)atanh.3 5.2 (Berkeley) 5/6/91 | |

.\" $FreeBSD: src/lib/msun/man/atanh.3,v 1.13 2005/01/28 21:14:16 ru Exp $ | |

.\" | |

.Dd January 14, 2005 | |

.Dt ATANH 3 | |

.Os | |

.Sh NAME | |

.Nm atanh , | |

.Nm atanhf | |

.Nd inverse hyperbolic tangent functions | |

.Sh LIBRARY | |

.Lb libm | |

.Sh SYNOPSIS | |

.In math.h | |

.Ft double | |

.Fn atanh "double x" | |

.Ft float | |

.Fn atanhf "float x" | |

.Sh DESCRIPTION | |

The | |

.Fn atanh | |

and the | |

.Fn atanhf | |

functions compute the inverse hyperbolic tangent | |

of the real | |

argument | |

.Ar x . | |

For a discussion of error due to roundoff, see | |

.Xr math 3 . | |

.Sh RETURN VALUES | |

The | |

.Fn atanh | |

and the | |

.Fn atanhf | |

functions | |

return the inverse hyperbolic tangent of | |

.Ar x | |

if successful. | |

If the argument has absolute value 1, a divide-by-zero exception | |

is raised and an infinity is returned. | |

If | |

.Ar |x| | |

> 1, an invalid exception is raised and an \*(Na is returned. | |

.Sh SEE ALSO | |

.Xr acosh 3 , | |

.Xr asinh 3 , | |

.Xr exp 3 , | |

.Xr fenv 3 , | |

.Xr math 3 | |

.Sh HISTORY | |

The | |

.Fn atanh | |

function appeared in | |

.Bx 4.3 . |