csin(3)

✨ csin(3) — the complex sine bestie era ✨

okay so this is csin(3), from the Library Functions Manual 💖. It's the page for csin, csinf and csinl — aka the complex sine function, but in three delicious flavors. 🍓

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🌈 LIBRARY

Math library, babes: link it with -lm. 📚

🎀 SYNOPSIS

#include <complex.h>

double complex csin(double complex z);
float complex csinf(float complex z);
long double complex csinl(long double complex z);

so yeah, three functions, three precisions: double complex, float complex, long double complex. pick your fighter 💅

👑 DESCRIPTION

These functions calculate the complex sine of z. That's it, that's the job. 🦋

The complex sine function is defined as:

csin(z) = (exp(i * z) - exp(-i * z)) / (2 * i)

like, that's the whole formula, no cap. it's giving Euler's formula energy and honestly? iconic. ✨

💜 ATTRIBUTES

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

• csin(), csinf(), csinl() — Thread safety: MT-Safe 🫶

so yes bestie, they're thread safe, you can go off with your threads. 🔥

🌸 STANDARDS

C11, POSIX.1-2008. certified and standardized, periodt. ⭐

🧚 HISTORY

Appeared in glibc 2.1. Before that, it was hanging out in C99 and POSIX.1-2001. it's been serving since forever, lowkey a legend. 💀✨

🌈 SEE ALSO

• cabs(3)
• casin(3)
• ccos(3)
• ctan(3)
• complex(7)

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mwah 💋 that's the whole page. this one comes from Linux man-pages 6.20, dated 2026-02-08, and it lives at csin(3). go forth and sine, queen 👑💅🌸