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ATANH(3) Linux Programmer's Manual ATANH(3)NAMEatanh, atanhf, atanhl - inverse hyperbolic tangent functionSYNOPSIS#include<math.h>doubleatanh(doublex);floatatanhf(floatx);longdoubleatanhl(longdoublex);Link with-lm. Feature Test Macro Requirements for glibc (see feature_test_macros(7)):atanh(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE; orcc-std=c99atanhf(),atanhl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; orcc-std=c99DESCRIPTIONTheatanh() function calculates the inverse hyperbolic tangent ofx; that is the value whose hyperbolic tangent isx.RETURNVALUEOn success, these functions return the inverse hyperbolic tangent ofx. Ifxis a NaN, a NaN is returned. Ifxis +0 (-0), +0 (-0) is returned. Ifxis +1 or -1, a pole error occurs, and the functions returnHUGE_VAL,HUGE_VALF, orHUGE_VALL, respec- tively, with the mathematically correct sign. If the absolute value ofxis greater than 1, a domain error occurs, and a NaN is returned.ERRORSSee math_error(7) for information on how to determine whether an error has occurred when calling these func- tions. The following errors can occur: Domain error:xless than -1 or greater than +1errnois set toEDOM. An invalid floating-point exception (FE_INVALID) is raised. Pole error:xis +1 or -1errnois set toERANGE. A divide-by-zero floating-point exception (FE_DIVBYZERO) is raised.CONFORMINGTOC99, POSIX.1-2001. The variant returningdoublealso conforms to SVr4, 4.3BSD, C89.SEEALSOacosh(3), asinh(3), catanh(3), cosh(3), sinh(3), tanh(3)COLOPHONThis page is part of release 3.22 of the Linuxman-pagesproject. A description of the project, and informa- tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. 2008-08-05 ATANH(3)