Anyone Know Where to Find Code That Solves Quartic Equations in Lua?

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#1

Hello,
I am currently looking for code that is able to solve quartic equations, most likely through inputting the coefficients of the equation. I would much prefer if this code source was in Lua as the code from what I have seen is long and complex math wise, which I would not want to translate back into Lua.

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#2

Unless you’re doing some second-degree derivative ballistic trajectory equation mumbo jumbo, I don’t see any practical use case for quartic equations within a Roblox game

I mean, if it looks like this I doubt anyone has converted a quartic formula into programming language form

image
image1677×766 96.9 KB

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#3

I am getting a turret to predict a path with gravity affecting the bullet. People have converted it, but not into Lua from what I’ve seen, which might take some time to convert.

#4

It looks like you’re going to be the first one to do so then.

There’s this article: https://github.com/CasualX/ProjectileSolverDemo

And then there’s also this:

Which claims to “compensate for gravity” which I’ve yet to test for myself

#5

He mentioned exponential gravity, is that some sort of pseudo gravity or just regular gravity?

#6

I have no idea; like I said, I haven’t tested the gravity compensation myself, only went as far as opening up the demo and having a peek

#7

I can’t really understand the language of the website you linked, it is using a language I have never used myself, but I did find a C written one. I am confused about one part of it. Each function has parameters of c and s, do you by any chance know what each might correlate too? I believe they are both arrays just don’t know what they are specified for.
(Was clicking on the wrong website somehow, looking over it now though)

#8

“c” appears to be the input and “s” is the output. The function themselves doesn’t return the solution, they instead plop it inside the “s” table which contains all real solutions

#9

Would c be ordered from greatest power to lowest power? For example 7x^2+3x+17 would go in as
[7, 3, 17]?

#10

Dude you have the source code in front of you

It also literally tells you that at the top within the comment block

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#11

Use rational root theorem.

#12

Hi

Yeah right now the module’s a bit broken, I’ll see if I can fix it and re-send the model
thanks for letting me know nonetheless

#13

Hi it’s me again so I just found this cool math module that uses Newton iteration to solve polynomials

It seems to be working fine for me (except for that duplicate answer)

ScreenShot_20220622121348
ScreenShot_202206221213481146×598 89.5 KB

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#15

Hi, would you mind giving the function you graphed in the image, I want to fix the duplicate answer problem and use that function to check if its fixed or not

#16 
0.1*x^4 + x^3 + 2.5*x^2 + 0.8*x - 1

Looking at your module it seems like you can fix it by adding a precision threshold for the hash table check so that minuscule differences won’t matter

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#17

Fixed, turns out math.round isnt practical when eliminating very similar answers from tables, thanks for the help!

#18

Just ended up translating the github I linked and works perfectly.

#19

you know i already did everything

also there was a native Lua formula for quartics, you just had to dig deeper

#20

We are using the same sources and the translation of the code doesn’t take long at all so honestly I’d rather write it myself, but thanks.