sinh(3)

💖 sinh(3) — hyperbolic sine but make it iconic 💖

okay bestie, welcome to the Library Functions Manual page for sinh(3) — yes that's the section 3 one, the math-y one, not some other imposter. sit down, grab a boba, we're doing hyperbolics. 🦋

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✨ NAME ✨

sinh, sinhf, sinhl — the hyperbolic sine function, and its float-y little siblings 🌸

✨ LIBRARY ✨

Math library (libm, link it with -lm — yes you have to, no it's not optional, we've all cried about it) 💅

✨ SYNOPSIS ✨

#include <math.h>

double sinh(double x);
float sinhf(float x);
long double sinhl(long double x);

🎀 Feature Test Macro Requirements for glibc (peep feature_test_macros(7) for the lore)

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

like, define one of these babies or the functions will simply not show up. it's giving gatekeeping bestie 😭

✨ DESCRIPTION ✨

These functions return the hyperbolic sine of x, which is mathematically defined as:

sinh(x) = (exp(x) - exp(-x)) / 2

that's it. that's the whole vibe. the difference of the exponentials, split straight down the middle. math ate and left no crumbs 👑

✨ RETURN VALUE ✨

• On success, you get the hyperbolic sine of x. slay. ✨
• If x is a NaN, you get a NaN back. NaN in, NaN out, no thoughts, head empty 🫶
• If x is +0 (-0), you get +0 (-0) back. it preserves the sign, respectful king behavior 💅
• If x is positive infinity (negative infinity), you get positive infinity (negative infinity) back. matching energy fr fr 🌈
• If the result overflows, a range error happens, and the functions return HUGE_VAL, HUGE_VALF, or HUGE_VALL respectively — all with the same sign as x. so it goes out loud, not quietly. 💥

✨ ERRORS ✨

Run, don't walk, to math_error(7) for the whole "how do I even know if an error happened" tutorial, bestie.

The errors that can occur:

• Range error: result overflow — errno gets set to ERANGE, and an overflow floating-point exception (FE_OVERFLOW) is raised. that's it, that's the error. 🚨

✨ ATTRIBUTES ✨

For what all these words even mean, see attributes(7). Basically:

• sinh(), sinhf(), sinhl() — Thread safety: MT-Safe. no cap, you can call these from multiple threads, they're chill like that 🧚

✨ STANDARDS ✨

C11, POSIX.1-2008. certified, licensed, official, iconic 👑

✨ HISTORY ✨

C99, POSIX.1-2001. ancient history bestie, but like, in a cute way.

The double-returning variant also conforms to SVr4, 4.3BSD, C89. it's been everywhere, it's a legend 💜

✨ SEE ALSO ✨

acosh(3), asinh(3), atanh(3), cosh(3), csinh(3), tanh(3) — the whole hyperbolic friend group, they roll deep 🍓

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that's the whole page bestie, you're officially a hyperbolic sine expert 💅

source check: this is Linux man-pages 6.20, dated 2026-02-08, for sinh(3). go forth and compute, and remember: -lm. always. 😭🫶✨