SIN(3P)

💖 SIN(3P) — the sine function, but make it a whole vibe 💖

okay bestie, so this page is SIN(3P) from the POSIX Programmer's Manual, and it's literally all about computing sines. let's get into it 🦋

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✨ PROLOG ✨

so like, heads up before anything else: this manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ — so if you're on Linux, go consult the corresponding Linux manual page for the deets on Linux behavior. also it's possible the interface just... isn't implemented on Linux at all. 😭 rude but true.

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🌸 NAME 🌸

sin, sinf, sinl — sine function. that's it, that's the girlboss trio 💅

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✨ SYNOPSIS ✨

#include <math.h>

double sin(double x);
float sinf(float x);
long double sinl(long double x);

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🎀 DESCRIPTION 🎀

okay 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 — no drama intended, promise. This volume of POSIX.1‐2017 defers to the ISO C standard. periodt.

These functions shall compute the sine of their argument x, measured in radians. (radians!! not degrees!! do not come for me.)

now listen, if you're an application wishing to check for error situations, you 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. that's your vibe check right there ⭐

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💜 RETURN VALUE 💜

Upon successful completion, these functions shall return the sine of x. slay.

• If x is NaN, a NaN shall be returned.
• If x is ±0, x shall be returned.
• If x is subnormal, a range error may occur and x should be returned.
• If x is not returned, sin(), sinf(), and sinl() shall return an implementation-defined value no greater in magnitude than DBL_MIN, FLT_MIN, and LDBL_MIN, respectively.
• If x is ±Inf, a domain error shall occur, and a NaN shall be returned. 💀

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🔥 ERRORS 🔥

These functions shall fail if:

• Domain Error — the x argument 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. (so like, no pressure, these are the bonus tracks 🎵)

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🌈 EXAMPLES 🌈

Taking the Sine of a 45-Degree Angle

#include <math.h>
...
double radians = 45.0 * M_PI / 180;
double result;
...
result = sin(radians);

45 degrees converted to radians and then sined. iconic behavior honestly 👑

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🫶 APPLICATION USAGE 🫶

These functions may lose accuracy when their argument is near a multiple of π or is far from 0.0. ngl that's just how it is sometimes 😭

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. they're doing their own thing but they do have to show up.

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🧚 RATIONALE 🧚

None.

(no thoughts, head empty, and honestly? respect. 💅)

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⭐ FUTURE DIRECTIONS ⭐

None.

(the future is undefined and that's on purpose ✨)

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🦋 SEE ALSO 🦋

• asin()
• feclearexcept()
• fetestexcept()
• isnan()

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 edition — mwah, drink some water, go compute a sine, ily 🫶💖✨