Implemented Thomas Algorithm in Lua

[Vexatos]

I chose not to mutate the input tables. Is that important?

[jiegillet]

It looks good, and not mutating the input is great. We should probably ask someone (paging @Gorzoid ) who knows lua for an actual review though.
One problem is how you print the system, it doesn't really work since a b and c are diagonal values of the matrix, not rows (and I realized you copied the Julia code, paging @leios ). If you want to prettify it, you can do something like the PHP implementation.

[Vexatos]

I just based this one on the Julia implementation.

[Gorzoid]

+1 for not mutating, another +1 for avoiding extra passes for shallow copies of the parameters, looks better than the julia code imo.
I agree with jie that we should properly print the augmented matrix, otherwise its very impossible to tell what each array is just by looking at the code.

[Gorzoid]

As jiegillet said, the system isn't actually this matrix. a,b and c are instead diagonals and d is the "result" column. To properly print the system we would need something like

print(b[1],	c[1], "",   "",   "|", d[1])
print("",   a[2], b[2], c[2], "|", d[2])
print("",   "",   a[3], b[3], "|", d[3])

I don't see much use in making code to properly any size augmented matrix so manually entering the indices should be fine.
It should be fine to use print(table.unpack(... for the solution however.

[Vexatos]

I agree, I based this on the Julia implementation. I will PR a fix to that as well I guess.

[Gorzoid]

I got no more issues SeemsGood

[leios]

It seems everyone is happy.