TANH(3P)

💖 PROLOG 💖

okay bestie, before literally anything else — this page? it's part of the POSIX Programmer's Manual, which is a whole vibe of its own. the Linux implementation of this interface may differ (so if you're on Linux, go check the corresponding Linux manual page for the actual tea ☕), or honestly the interface might not even be implemented on Linux at all. no cap. 🙈

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✨ NAME ✨

tanh, tanhf, tanhl — the hyperbolic tangent functions, aka the trio you're about to be obsessed with 🎀

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🦋 SYNOPSIS 🦋

#include <math.h>

double tanh(double x);
float tanhf(float x);
long double tanhl(long double x);

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🌸 DESCRIPTION 🌸

okay so here's the situation. the functionality described on this reference page is aligned with the ISO C standard. any conflict between the requirements described here and the ISO C standard is unintentional — nobody's trying to start drama. this volume of POSIX.1-2017 defers to the ISO C standard, periodt.

these functions shall compute the hyperbolic tangent of their argument x. iconic behavior fr fr. 💅

and now the important part, bestie, listen up 👑 — an application wishing to check for error situations should set errno to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these functions. then on return: if errno is non-zero, or if fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred. that's the vibe check right there. 🔥

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💜 RETURN VALUE 💜

upon successful completion, these functions shall return the hyperbolic tangent of x. slay.

• if x is NaN, a NaN shall be returned. 🫠
• if x is ±0, x shall be returned.
• if x is ±Inf, ±1 shall be returned.
• if x is subnormal, a range error may occur and x should be returned.

and if x is not returned? then tanh(), tanhf(), and tanhl() shall return an implementation-defined value no greater in magnitude than DBL_MIN, FLT_MIN, and LDBL_MIN, respectively. write that down bestie 📝

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😭 ERRORS 😭

these functions may fail if:

• Range Error — the value of x is subnormal.

if the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [ERANGE]. if the integer expression (math_errhandling & MATH_ERRREXCEPT) is non-zero, then the underflow floating-point exception shall be raised. ⚠️

the following sections are informative. so like, they're the bonus content, not the main plot. 🍓

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🧚 EXAMPLES 🧚

None.

(i know. i know. the audacity. 💀)

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🌈 APPLICATION USAGE 🌈

on error, the expressions (math_errhandling & MATH_ERRNO) and (math_errhandling & MATH_ERRREXCEPT) are independent of each other — they don't text each other, they don't follow each other, nothing. but at least one of them must be non-zero. that's the rule. 🤝

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🎀 RATIONALE 🎀

None.

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⭐ FUTURE DIRECTIONS ⭐

None.

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🫶 SEE ALSO 🫶

• atanh()
• feclearexcept()
• fetestexcept()
• isnan()
• tan()

also: The Base Definitions volume of POSIX.1-2017, Section 4.20, Treatment of Error Conditions for Mathematical Functions, <math.h> 💖

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👑 COPYRIGHT 👑

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .

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and that's the whole page bestie, we ate and left no crumbs 💅✨ this one's brought to you by IEEE/The Open Group, dated 2017, and it lives under the name TANH(3P) in the POSIX Programmer's Manual. mwah 🫶🌷