csinh(3)

✨ csinh — complex hyperbolic sine, but make it a vibe ✨

okay so bestie, you're in the csinh(3) page 💖 this is from the Library Functions Manual, and we're about to get so cozy with the complex hyperbolic sine. i promise this is less scary than it sounds, fr fr 🦋

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🎀 NAME 🎀

csinh, csinhf, csinhl — the complex hyperbolic sine (yes, three of them, one for each flavor of float 💅)

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📚 LIBRARY 📚

Math library — link it with libm, aka -lm 🧮

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🌸 SYNOPSIS 🌸

#include <complex.h>

double complex csinh(double complex z);
float complex csinhf(float complex z);
long double complex csinhl(long double complex z);

ok so you literally just pick your precision and go 👑 no cap, that's the whole intro.

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💫 DESCRIPTION 💫

These functions calculate the complex hyperbolic sine of z. that's it, that's the job, and they do it flawlessly 💅

The complex hyperbolic sine function is defined as:

csinh(z) = (exp(z)-exp(-z))/2

like, it's giving classic definition energy — exp on both ends, a little subtraction moment, divide by two, slay ✨

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🔥 ATTRIBUTES 🔥

ngl, for the whole explanation of the terminology used in this section, you gotta go check out attributes(7) — go read it, i'll wait 🫶

• csinh(), csinhf(), csinhl() — Thread safety: MT-Safe 👑

so yes bestie, they are MT-Safe, meaning you can call them from multiple threads and nobody's gonna fight, periodt 🌈

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⭐ STANDARDS ⭐

C11, POSIX.1-2008 💜

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🦋 HISTORY 🦋

• glibc 2.1 — this is when it showed up in glibc, iconic behavior honestly 🌸
• C99, POSIX.1-2001 — and that's where it was standardized, iykyk 📜

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👀 SEE ALSO 👀

• cabs(3)
• casinh(3)
• ccosh(3)
• ctanh(3)
• complex(7)

go read those too, they're all in the same friend group 💖

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⚠️ real talk: csinh(z) = (exp(z)-exp(-z))/2 is the actual definition and the actual behavior — don't go inventing your own, the math is not a vibe, it's a law 😭

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and that's the whole page, bestie!! this was Linux man-pages 6.20, dated 2026-02-08, page csinh(3) — go forth and compute your complex hyperbolic sines, i'm obsessed with you 🎀💜🧚✨