ASIN(3POSIX)

🌸 ASIN(3POSIX) — the arc sine glow-up 🌸

okay bestie, welcome to the POSIX Programmer's Manual entry for ASIN(3POSIX), and it's giving "math but make it ✨specified✨". Quick heads up before we dive in: this page is part of the POSIX Programmer's Manual, so the Linux implementation of this interface may differ (bestie, consult the corresponding Linux manual page for the details, no cap), or the interface might not even be implemented on Linux at all. 💀

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🦋 PROLOG 🦋

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

tl;dr — this is the POSIX lore, not necessarily your Linux box's lore. Check the local page before you start beefing with your compiler. ✨

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💖 NAME 💖

asin, asinf, asinl — arc sine function

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✨ SYNOPSIS ✨

#include <math.h>

double asin(double x);
float asinf(float x);
long double asinl(long double x);

three flavors, same vibe, different precision. pick your fighter. 💅

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🎀 DESCRIPTION 🎀

so 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 — literally not on purpose, we promise. This volume of POSIX.1‐2017 defers to the ISO C standard. periodt.

These functions shall compute the principal value of the arc sine of their argument x. The value of x should be in the range [-1,1] — stay in your lane, babe, that's the domain. 🌈

An application wishing to check for error situations should set errno to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if errno is non-zero or fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred. it's giving "vibe check your floating-point exceptions before you spiral". 🔍

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👑 RETURN VALUE 👑

Upon successful completion, these functions shall return the arc sine of x, in the range [-π/2,π/2] radians. slay. ✨

• For finite values of x 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. (garbage in, garbage out, but make it standards-compliant 💀)
• If x is ±0, x shall be returned.
• If x is ±Inf, a domain error shall occur, and a NaN shall be returned.
• If x is subnormal, a range error may occur and x should be returned.
• If x is not returned, asin(), asinf(), and asinl() shall return an implementation-defined value no greater in magnitude than DBL_MIN, FLT_MIN, and LDBL_MIN, respectively.

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😭 ERRORS 😭

These functions shall fail if:

• Domain Error — The x argument is finite and is not in the range [-1,1], or is ±Inf.

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

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_ERREXCEPT) is non-zero, then the underflow floating-point exception shall be raised.

The following sections are informative. 📝

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🍓 EXAMPLES 🍓

None.

(not one single example. iconic restraint honestly. 🙈)

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🧚 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. so like, they don't talk to each other, but somebody has to show up to the party. 🫶

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💜 RATIONALE 💜

None.

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🌈 FUTURE DIRECTIONS 🌈

None.

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⭐ SEE ALSO ⭐

• feclearexcept()
• fetestexcept()
• isnan()
• sin()

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 — brought to you by IEEE/The Open Group, 2017, ASIN(3POSIX), arc sine and all its little siblings. go compute some angles responsibly. 💅✨