ACOS(3P)

πŸ“¦ version 2017a, in alpine 3.22, alpine 3.23, alpine 3.24, arch rolling, nixpkgs unstable, opensuse-leap 16.0

πŸ‘‘ ACOS(3P) β€” the arc cosine glow-up πŸ’…

okay bestie, welcome to ACOS(3P), straight out of the POSIX Programmer's Manual ✨. It's giving math.h main character energy and we're gonna read it together, fr fr.

🌸 PROLOG 🌸

This manual page is part of the POSIX Programmer's Manual. Heads up though β€” the Linux implementation of this interface may differ (so go consult the corresponding Linux manual page for the details of Linux behavior if that's your situation), or honestly the interface may not be implemented on Linux at all. πŸ™ˆ

πŸŽ€ NAME πŸŽ€

acos, acosf, acosl β€” arc cosine functions. that's the whole vibe. πŸ¦‹

✨ SYNOPSIS ✨

#include <math.h>

double acos(double x);
float acosf(float x);
long double acosl(long double x);

πŸ’– DESCRIPTION πŸ’–

So the functionality described on this reference page is aligned with the ISO C standard. And like, any conflict between the requirements described here and the ISO C standard is unintentional β€” not a vibe, not on purpose. This volume of POSIX.1‐2017 defers to the ISO C standard. periodt.

These functions shall compute the principal value of the arc cosine of their argument x. And the value of x should be in the range [-1,1] β€” stay in your lane, bestie. 🎯

Now, if your application wants to check for error situations, here's the move: 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 β€” an error has occurred. no cap. 😭

πŸ”₯ RETURN VALUE πŸ”₯

Upon successful completion, these functions shall return the arc cosine of x, in the range [0,Ο€] radians. slay.

For finite values of x that are not in the range [-1,1], a domain error shall occur, and either a NaN (if supported) or an implementation-defined value shall be returned. 😬

If x is NaN, a NaN shall be returned.

If x is +1, +0 shall be returned.

If x is Β±Inf, a domain error shall occur, and a NaN shall be returned.

πŸ’€ ERRORS πŸ’€

These functions shall fail if:

Domain Error

The x argument is finite and is not in the range [-1,1], or is Β±Inf.

If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [EDOM]. And if the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception shall be raised. 🚨

The following sections are informative. (just so you know, bestie β€” these are the chill bonus sections 🫢)

🌈 EXAMPLES 🌈

None. πŸ’€ literally nothing. iconic of them honestly.

🧚 APPLICATION USAGE 🧚

On error, the expressions (math_errhandling & MATH_ERRNO) and (math_errhandling & MATH_ERREXCEPT) are independent of each other β€” but at least one of them must be non-zero. that's the rule, don't fight it. βœ‹

⭐ RATIONALE ⭐

None. (they said "no thoughts, head empty" and honestly? respect. πŸ™ˆ)

πŸ“ FUTURE DIRECTIONS πŸ“

None. the future is undefined and that's on purpose.

πŸ’œ SEE ALSO πŸ’œ

  • cos()
  • feclearexcept()
  • fetestexcept()
  • isnan()

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

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 .

okay that's the whole page, bestie β€” go compute some arc cosine and be your most radiant self 🌸 IEEE/The Open Group, 2017 πŸ’– mwah πŸ’‹

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