COSH(3P)

<h1>💖 cosh, coshf, coshl — the hyperbolic cosine glow-up 💖</h1>

okay so bestie, you've wandered into COSH(3P), which is a page from the POSIX Programmer's Manual 🫶. buckle up, we're doing math today and it's gonna be adorable.

---

🌸 PROLOG 🌸

so like, this manual page is part of the POSIX Programmer's Manual. heads up tho: the Linux implementation of this interface may differ — if you're on Linux, go peek at the corresponding Linux manual page for the actual Linux behavior. or, plot twist, the interface might not even be implemented on Linux at all. 😭 not me finding out the hard way.

---

✨ NAME ✨

cosh, coshf, coshl — hyperbolic cosine functions. that's it, that's the name, three little icons of math 💅

---

🎀 SYNOPSIS 🎀

#include <math.h>

double cosh(double x);
float coshf(float x);
long double coshl(long double x);

three flavors, same vibe: double, float, long double. choose your fighter ⭐

---

🦋 DESCRIPTION 🦋

the functionality described on this reference page is aligned with the ISO C standard. any conflict between what's written here and the ISO C standard? not intentional, fr fr. this volume of POSIX.1‐2017 defers to the ISO C standard. periodt.

these functions shall compute the hyperbolic cosine of their argument x. iconic behavior honestly.

now, the checking-for-errors ritual 🧚: 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 fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero — an error has occurred. slay, you caught it.

---

🔥 RETURN VALUE 🔥

upon successful completion, these functions shall return the hyperbolic cosine of x. cute, correct, no notes.

if the correct value would cause overflow, a range error shall occur and cosh(), coshf(), and coshl() shall return the value of the macro HUGE_VAL, HUGE_VALF, and HUGE_VALL, respectively. big number energy, literally 💀

• if x is NaN, a NaN shall be returned.
• if x is ±0, the value 1.0 shall be returned.
• if x is ±Inf, +Inf shall be returned.

---

👑 ERRORS 👑

these functions shall fail if:

• Range Error — the result would cause an overflow.
  • 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_ERREXCEPT) is non-zero, then the overflow floating-point exception shall be raised.

the following sections are informative. (yes, that's a real line from the original, and yes, it means what it says 🫶)

---

🌈 EXAMPLES 🌈

None. 😭 the void, the emptiness, the no examples. we simply have none.

---

💜 APPLICATION USAGE 💜

on error, the expressions (math_errhandling & MATH_ERRNO) and (math_errhandling & MATH_ERREXCEPT) are independent of each other — but at least one of them must be non-zero. no cap.

---

🍓 RATIONALE 🍓

None. that's the whole rationale. she said nothing and left 💅

---

⭐ FUTURE DIRECTIONS ⭐

None. the future is bright and also empty.

---

🧚 SEE ALSO 🧚

• acosh()
• feclearexcept()
• fetestexcept()
• isnan()
• sinh()
• tanh()
• The Base Definitions volume of POSIX.1‐2017, Section 4.20, Treatment of Error Conditions for Mathematical Functions, <math.h>

the whole hyperbolic friend group, together at last 🫶

---

💖 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 .

---

and that's the whole page bestie 💅 this one came to you courtesy of IEEE/The Open Group, dated 2017, and it lives under the name COSH(3P) in the POSIX Programmer's Manual. mwah, go forth and compute 🌸