1TANH(3P)                   POSIX Programmer's Manual                  TANH(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

13       tanh, tanhf, tanhl — hyperbolic tangent functions
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SYNOPSIS

16       #include <math.h>
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18       double tanh(double x);
19       float tanhf(float x);
20       long double tanhl(long double x);
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DESCRIPTION

23       The functionality described on this reference page is aligned with  the
24       ISO C  standard.  Any  conflict between the requirements described here
25       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2008
26       defers to the ISO C standard.
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28       These  functions shall compute the hyperbolic tangent of their argument
29       x.
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31       An application wishing to check for error situations should  set  errno
32       to  zero  and  call  feclearexcept(FE_ALL_EXCEPT)  before calling these
33       functions. On return, if errno is non-zero or fetestexcept(FE_INVALID |
34       FE_DIVBYZERO  |  FE_OVERFLOW  | FE_UNDERFLOW) is non-zero, an error has
35       occurred.
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RETURN VALUE

38       Upon successful completion, these functions shall return the hyperbolic
39       tangent of x.
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41       If x is NaN, a NaN shall be returned.
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43       If x is ±0, x shall be returned.
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45       If x is ±Inf, ±1 shall be returned.
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47       If x is subnormal, a range error may occur
48       and x should be returned.
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50       If  x  is  not  returned,  tanh(), tanhf(), and tanhl() shall return an
51       implementation-defined value no  greater  in  magnitude  than  DBL_MIN,
52       FLT_MIN, and LDBL_MIN, respectively.
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ERRORS

55       These functions may fail if:
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57       Range Error The value of x is subnormal.
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59                   If  the  integer expression (math_errhandling & MATH_ERRNO)
60                   is non-zero, then errno shall be set to [ERANGE].   If  the
61                   integer  expression  (math_errhandling & MATH_ERREXCEPT) is
62                   non-zero, then the underflow floating-point exception shall
63                   be raised.
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65       The following sections are informative.
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EXAMPLES

68       None.
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APPLICATION USAGE

71       On   error,   the   expressions  (math_errhandling  &  MATH_ERRNO)  and
72       (math_errhandling & MATH_ERREXCEPT) are independent of each other,  but
73       at least one of them must be non-zero.
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RATIONALE

76       None.
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FUTURE DIRECTIONS

79       None.
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SEE ALSO

82       atanh(), feclearexcept(), fetestexcept(), isnan(), tan()
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84       The Base Definitions volume of POSIX.1‐2008, Section 4.19, Treatment of
85       Error Conditions for Mathematical Functions, <math.h>
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88       Portions of this text are reprinted and reproduced in  electronic  form
89       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
90       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
91       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
92       cal and Electronics Engineers,  Inc  and  The  Open  Group.   (This  is
93       POSIX.1-2008  with  the  2013  Technical Corrigendum 1 applied.) In the
94       event of any discrepancy between this version and the original IEEE and
95       The  Open Group Standard, the original IEEE and The Open Group Standard
96       is the referee document. The original Standard can be  obtained  online
97       at http://www.unix.org/online.html .
98
99       Any  typographical  or  formatting  errors that appear in this page are
100       most likely to have been introduced during the conversion of the source
101       files  to  man page format. To report such errors, see https://www.ker‐
102       nel.org/doc/man-pages/reporting_bugs.html .
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106IEEE/The Open Group                  2013                             TANH(3P)
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