fixacos(3alleg4)

💖 fixacos — the fixed point inverse cosine lookup table, bestie 💖

Allegro manual · fixacos(3alleg4) · a whole function from the Allegro game programming library 🎀

✨ NAME ✨

fixacos — fixed point inverse cosine lookup table. Allegro game programming library. 🦋

🌸 SYNOPSIS 🌸

#include <allegro.h>

fixed fixacos(fixed x);

👑 DESCRIPTION 👑

okay so. this function finds the inverse cosine of a value using a lookup table. no cap, it's literally a table lookup. 🧚

your input value must be a fixed point radian. and listen — inverse cosine is only defined in the domain from -1 to 1. that's it, that's the whole vibe check. if you go outside that input range, the function will set errno to EDOM and return zero. 💀

example, because we love a demonstration:

fixed result;

/* Sets `result' to binary angle 128. */
result = fixacos(itofix(-1));

💅 RETURN VALUE 💅

returns the inverse sine of a fixed point value, measured as fixed point binary format angle, or zero if the input was out of range. (yes, the page says inverse sine — that's what it says, i'm just the messenger 🙈)

all return values of this function will be in the range 0 to 128. every single one. periodt. ⭐

🌈 SEE ALSO 🌈

that's it, bestie — nothing else listed on this one 🫶

lowkey the whole thing in one breath: radian-ish fixed input, -1 to 1 only, else errno = EDOM and you get a zero back. 💜

Allegro version 4.4.3 · fixacos(3alleg4) — mwah, tysm for reading, go slay some fixed point math 💖✨🎀