asinh(3)

✨ asinh — bestie, we're going INVERSE ✨

okay so the manual name here is asinh(3) and the whole vibe is inverse hyperbolic sine 💖 it's a math library situation, libm, and yes you link it with -lm like always, you know the drill 🫶

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🌸 NAME 🌸

asinh, asinhf, asinhl — the inverse hyperbolic sine function, in three delicious flavors: double, float, and long double 🍓

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📚 LIBRARY 📚

Math library (libm, -lm) — gotta bring the -lm to the party or nothing works, fr fr.

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🎀 SYNOPSIS 🎀

#include <math.h>

double asinh(double x);
float asinhf(float x);
long double asinhl(long double x);

✨ Feature Test Macro Requirements for glibc ✨

(this is the glibc edition, see feature_test_macros(7) for the whole tea ☕)

asinh():

_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
    || _XOPEN_SOURCE >= 500
    || /* Since glibc 2.19: */ _DEFAULT_SOURCE
    || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

asinhf(), asinhl():

_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
    || /* Since glibc 2.19: */ _DEFAULT_SOURCE
    || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

like… pick one of those, bestie, and you're golden 💅

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💜 DESCRIPTION 💜

These functions calculate the inverse hyperbolic sine of x. Which is a fancy way of saying: they hand you back the value whose hyperbolic sine is x. It's giving "un-sinh", and it ate ✨

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🔥 RETURN VALUE 🔥

On success, these functions return the inverse hyperbolic sine of x. periodt.

• If x is a NaN, a NaN is returned. 💀 (went in weird, came out weird)
• If x is +0 (-0), +0 (-0) is returned. our zero keeps its sign, iconic behavior 👑
• If x is positive infinity (negative infinity), positive infinity (negative infinity) is returned. symmetry slay 🌈

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😭 ERRORS 😭

No errors occur. Not a single one. Nothing to report. The drama-free function of the century 🧚

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⭐ ATTRIBUTES ⭐

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

• asinh(), asinhf(), asinhl() — Thread safety: MT-Safe 🫶 (yes, all three of them, they're all safe to share, go wild)

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🌟 STANDARDS 🌟

C11, POSIX.1-2008. no cap.

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🦋 HISTORY 🦋

C99, POSIX.1-2001.

Also, the variant returning double also conforms to SVr4, 4.3BSD. it's old money, it's been around, it's a legacy queen 💅

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👀 SEE ALSO 👀

acosh(3), atanh(3), casinh(3), cosh(3), sinh(3), tanh(3) — the whole hyperbolic friend group, go say hi 🎀

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and that's the whole page bestie!! 💖 this was the asinh(3) manual page from Linux man-pages 6.20, dated 2026-02-08 — mwah, go compute something, ily 🫶✨