SQRT(3POSIX)

💖 PROLOG 💖

okay bestie, real talk before we get into the math: this manual page is part of the POSIX Programmer's Manual 🌈. The Linux implementation of this interface may differ (so like, go check the corresponding Linux manual page for the details of Linux behavior), or honestly the interface might not even be implemented on Linux at all. rude, but okay. 💀

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✨ NAME ✨

sqrt, sqrtf, sqrtl — square root function 🍓

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🦋 SYNOPSIS 🦋

#include <math.h>

double sqrt(double x);
float sqrtf(float x);
long double sqrtl(long double x);

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👑 DESCRIPTION 👑

okay 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 (we're not starting drama on purpose, promise 🫶). This volume of POSIX.1‐2017 defers to the ISO C standard.

These functions shall compute the square root of their argument x, that's √x. iconic behavior honestly.

not me about to tell you the error-checking ritual: 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 careful. it's giving slay. 💅

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🔥 RETURN VALUE 🔥

Upon successful completion, these functions shall return the square root of x. periodt.

For finite values of x < -0, 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. (NaN in, NaN out, that's the vibe.)

If x is ±0 or +Inf, x shall be returned. no thoughts, just identity.

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 finite value of x is < -0, or x 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.

The following sections are informative. (translation: the vibes section starts here, the rules part is over 🎀)

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🧚 EXAMPLES 🧚

Taking the Square Root of 9.0

#include <math.h>
...
double x = 9.0;
double result;
...
result = sqrt(x);

three. the answer is three. you're welcome bestie 💜

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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 text each other, but one of them HAS to show up to the party. iykyk.

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💅 RATIONALE 💅

None.

(the original literally just says that. no notes. we respect the minimalism. ✨)

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⭐ FUTURE DIRECTIONS ⭐

None.

(again, verbatim. the future is empty and honestly that's so real of it.)

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🫶 SEE ALSO 🫶

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

The Base Definitions volume of POSIX.1‐2017, Section 4.20, Treatment of Error Conditions for Mathematical Functions, <math.h>, <stdio.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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ok that's the whole page bestie, we ate and left no crumbs 💖

and a lil sign-off for the record: this one's from IEEE/The Open Group, dated 2017, and yes the manual name is SQRT(3POSIX) in case you were wondering what you just read. now go take some square roots, you icon. 🦋✨