ccos(3)

💖 ccos — complex cosine, but make it serve 💖

okay bestie, come sit with me, because today we are cosining... complexly. ✨ this little page is about ccos, plus its two glow-up twins ccosf and ccosl — the complex cosine function. yes, complex as in complex numbers, not complex as in "why is math like this". 🦋

📚 LIBRARY

the math library, babes: libm, which you link with -lm. (the l is for "love", probably. it's for library. whatever. 🫶)

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✨ SYNOPSIS ✨

first you gotta invite the header to the party:

#include <complex.h>

then here are the three icons themselves, in all their glory:

double complex ccos(double complex z);
float complex ccosf(float complex z);
long double complex ccosl(long double complex z);

like, ccos for double complex, ccosf for float complex, ccosl for long double complex. the f and l suffixes are basically the outfit changes. 💅

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🌸 DESCRIPTION 🌸

these functions calculate the complex cosine of z. that's it. that's the job. no cap.

and because the vibes must be mathematically rigorous, the complex cosine function is defined as:

ccos(z) = (exp(i * z) + exp(-i * z)) / 2

look at her. two exponentials, one imaginary unit, a lil sum, divided by two. it's giving Euler's formula energy and honestly? obsessed. 🎀

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👑 ATTRIBUTES 👑

for an explanation of the terms used in this section, go read attributes(7) — it's the glossary, bestie, it explains what all these words mean.

• ccos(), ccosf(), ccosl() — Thread safety: MT-Safe. translation: she is safe to use across multiple threads, she does not start drama, she does not corrupt your data. a well-behaved queen. 👑

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⭐ STANDARDS ⭐

• C11
• POSIX.1-2008

so yes, she's officially certified. standards-approved. the committee said "slay" and put it in writing. 📜✨

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🦋 HISTORY 🦋

• glibc 2.1 — when she first arrived on the scene.
• C99, POSIX.1-2001 — the standards she's been repping for ages.

she's been iconic since glibc 2.1 and she has NOT slowed down. veteran behavior. 🫶

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🔥 SEE ALSO 🔥

the whole extended universe, go read them:

• cabs(3)
• cacos(3)
• csin(3)
• ctan(3)
• complex(7)

complex(7) is literally the group chat — start there if you're new here. iykyk. 💜

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and that's the whole page, bestie!! this one came from Linux man-pages 6.20, dated 2026-02-08 — so you know it's fresh. drink water, link with -lm, and go cosine something complex. mwah. 💖✨🎀