1ATANH(3) Linux Programmer's Manual ATANH(3)
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6 atanh, atanhf, atanhl - inverse hyperbolic tangent function
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9 #include <math.h>
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11 double atanh(double x);
12 float atanhf(float x);
13 long double atanhl(long double x);
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15 Link with -lm.
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17 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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19 atanh(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
20 _ISOC99_SOURCE; or cc -std=c99
21 atanhf(), atanhl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600
22 || _ISOC99_SOURCE; or cc -std=c99
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25 The atanh() function calculates the inverse hyperbolic tangent of x;
26 that is the value whose hyperbolic tangent is x.
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29 On success, these functions return the inverse hyperbolic tangent of x.
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31 If x is a NaN, a NaN is returned.
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33 If x is +0 (-0), +0 (-0) is returned.
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35 If x is +1 or -1, a pole error occurs, and the functions return
36 HUGE_VAL, HUGE_VALF, or HUGE_VALL, respectively, with the mathemati‐
37 cally correct sign.
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39 If the absolute value of x is greater than 1, a domain error occurs,
40 and a NaN is returned.
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43 See math_error(7) for information on how to determine whether an error
44 has occurred when calling these functions.
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46 The following errors can occur:
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48 Domain error: x less than -1 or greater than +1
49 errno is set to EDOM. An invalid floating-point exception
50 (FE_INVALID) is raised.
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52 Pole error: x is +1 or -1
53 errno is set to ERANGE. A divide-by-zero floating-point excep‐
54 tion (FE_DIVBYZERO) is raised.
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57 C99, POSIX.1-2001. The variant returning double also conforms to SVr4,
58 4.3BSD, C89.
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61 acosh(3), asinh(3), catanh(3), cosh(3), sinh(3), tanh(3)
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64 This page is part of release 3.22 of the Linux man-pages project. A
65 description of the project, and information about reporting bugs, can
66 be found at http://www.kernel.org/doc/man-pages/.
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70 2008-08-05 ATANH(3)