sqrt(3)

💖 sqrt(3) — the square root girlies 💖

okay so bestie, this is the manual for sqrt(3), from the Library Functions Manual (that's the section 3 girlies, the library calls, we love them). she's literally the square root function and she's been carrying math since forever 🫶

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✨ NAME ✨

sqrt, sqrtf, sqrtl — square root function

📚 LIBRARY 📚

Math library (libm, -lm)

not me reminding you to link with -lm because the linker WILL be dramatic about it 💀

🌸 SYNOPSIS 🌸

#include <math.h>

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

🦋 Feature Test Macro Requirements for glibc 🦋

(see feature_test_macros(7) for the whole lore)

sqrtf(), sqrtl():
    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

like yes queen, define one of those or she simply will not show up 🙈

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💅 DESCRIPTION 💅

These functions return the nonnegative square root of x. that's the vibe. positive root only, she does not do negative, we've talked about this 😭

🔥 RETURN VALUE 🔥

On success, these functions return the square root of x. iconic behavior honestly ✨

• If x is a NaN, a NaN is returned.
• If x is +0 (-0), +0 (-0) is returned.
• If x is positive infinity, positive infinity is returned.
• If x is less than -0, a domain error occurs, and a NaN is returned. 🚨

😭 ERRORS 😭

See math_error(7) for information on how to determine whether an error has occurred when calling these functions. (iykyk)

The following errors can occur:

• Domain error: x less than -0 — errno is set to EDOM. An invalid floating-point exception (FE_INVALID) is raised.

bestie you literally cannot sqrt a negative and get a real one, she said no thank u 💀💅

👑 ATTRIBUTES 👑

For an explanation of the terms used in this section, see attributes(7).

• sqrt(), sqrtf(), sqrtl() — Thread safety — MT-Safe 🎀

MT-Safe means she's safe to use from multiple threads at once, no drama, we stan a secure queen ✨

🌈 STANDARDS 🌈

C11, POSIX.1-2008.

🧚 HISTORY 🧚

C99, POSIX.1-2001.

The variant returning double also conforms to SVr4, 4.3BSD, C89. she's been certified for a MINUTE, respect the elders 💜

⭐ SEE ALSO ⭐

cbrt(3), csqrt(3), hypot(3)

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okay that's the whole page bestie! this was the Linux man-pages 6.20 release, dated 2026-02-08, and the page is sqrt(3) — go forth and take square roots responsibly, mwah 💖✨🎀