SQRT(3)

💖 SQRT(3) — cube root, square root, and inverse square root functions 💖

okay bestie, welcome to the SQRT(3) page from the Library Functions Manual — the math girlies are literally right here and they are serving roots. 🧮✨

🌸 NAME 🌸

Bestie, meet the lineup: cbrt, cbrtf, cbrtl, rsqrt, rsqrtf, rsqrtl, sqrt, sqrtf, sqrtl — these are your cube root, square root, and inverse square root functions. periodt. 💅

🧚 LIBRARY 🧚

Math Library (libm, -lm) — that's the address, and yes you link it with -lm. 🫶

✨ SYNOPSIS ✨

#include <math.h>

double
cbrt(double x);

float
cbrtf(float x);

long double
cbrtl(long double x);

double
rsqrt(double x);

float
rsqrtf(float x);

long double
rsqrtl(long double x);

double
sqrt(double x);

float
sqrtf(float x);

long double
sqrtl(long double x);

🦋 DESCRIPTION 🦋

Listen, it's giving “three little families, three big jobs”:

• cbrt(), cbrtf(), cbrtl() — compute the cube root of x. 🧊
• rsqrt(), rsqrtf(), rsqrtl() — compute the inverse square root of x. 🔄
• sqrt(), sqrtf(), sqrtl() — compute the non-negative square root of x. 🌱

🔥 RETURN VALUES 🔥

• cbrt(), cbrtf(), cbrtl() — return the requested cube root. no drama. 🎀
• rsqrt(), rsqrtf(), rsqrtl() — return 1 divided by the square root of x unless an error occurs. an attempt to take the rsqrt() of negative x raises an invalid exception and causes an NaN to be returned. the inverse square root of ±0 returns ±∞ and raises a divide-by-zero exception. 💀⚠️
• sqrt(), sqrtf(), sqrtl() — return the requested square root unless an error occurs. an attempt to take the sqrt() of negative x raises an invalid exception and causes an NaN to be returned (except that the square root of -0 is valid and equal to -0.) 👑

🌈 SEE ALSO 🌈

fenv(3), math(3) — go say hi. 👋

🎀 STANDARDS 🎀

cbrt(), cbrtf(), cbrtl(), sqrt(), sqrtf(), and sqrtl() conform to ISO/IEC 9899:1999 (“ISO C99”). the rsqrt(), rsqrtf(), and rsqrtl() functions conform to ISO/IEC 9899:2024 ("ISO C23"). ✨ slay and standardize ✨ 📚

🕰️ HISTORY 🕰️

the tea: cbrt() appeared in 4.3BSD. sqrt() appeared in Version 2 AT&T UNIX. sqrtl() appeared in FreeBSD 8.0. cbrtl() appeared in FreeBSD 9.0. rsqrt(), rsqrtf(), and rsqrtl() appeared in FreeBSD 16.0. ancient roots, fresh fits. 👑🫶

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mwah 💋 — source/version: Debian, date: May 7, 2026, page: SQRT(3). now go be iconic with your roots 🍓✨