3057 posts
Location
United States of America
Posted 22 October 2015 - 03:46 PM
I've been trying to do this for 3 or 4 days now, and it's stalling my current project. I would like a function which, when passed a table of arguments in the format [power] = coefficient and a number, it will use synthetic division to create a new table in the same format, which it returns.
If you don't know what Synthetic Division is, you can learn more about it
here.
7083 posts
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Tasmania (AU)
Posted 23 October 2015 - 03:14 AM
Can you provide sample input/output for this function?
3057 posts
Location
United States of America
Posted 23 October 2015 - 05:12 AM
Yes, of course!
--[[ just me making an equation up
(x+3)(x^2+3x+1)
x^3+6x^2+9x+3
]]--
--#notice this is in the format ax^b, where tbl[ b ] = a
local input_tbl = {
[0]=3,
9,
6,
1,
}
local input_num = -3 --#negative three is a real solution to the problem; I will always pass it real solutions.
--#some function
local result = {
[0]=1,
3,
1,
}
If that isn't clear enough, please let me know.
Edited on 23 October 2015 - 03:16 AM
496 posts
Location
New Zealand
Posted 23 October 2015 - 10:14 AM
--[[ just me making an equation up
(x+3)(x^2+3x+1)
x^3+6x^2+9x+3
]]--
Wanted to point out your math is wrong, it should be 10x not 9x.
And here's it implemented in lua:
https://gist.github.com/Xtansia/e4e30318b890ea1dfdfesynthetic_division returns the result polynomial table and the remainder.
Also added a function for converting the polynomial coefficient table into a string of the polynomial.
3057 posts
Location
United States of America
Posted 23 October 2015 - 01:59 PM
Thanks! The only problem I've discovered is the polynomial_tostring doesn't like it if something is missing.
For example, this table was generated by your polynomial division:
{
[3] = 1,
[2] = 6,
[0] = -1,
}
Edited on 23 October 2015 - 11:59 AM
524 posts
Location
Cambridge, England
Posted 23 October 2015 - 02:13 PM
This seems suspiciously like you're trying to get help with school homework!
496 posts
Location
New Zealand
Posted 23 October 2015 - 02:18 PM
Thanks! The only problem I've discovered is the polynomial_tostring doesn't like it if something is missing.
Oh, right fixed the gist.
Line 25 just needed 'or 0' added to the end, like so:
local coeff = polynomial[i] or 0
2679 posts
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You will never find me, muhahahahahaha
Posted 23 October 2015 - 02:29 PM
This seems suspiciously like you're trying to get help with school homework!
Is it forbidden? As long as we can find a cheap way to connect it to programming.
Edited on 23 October 2015 - 12:29 PM
3057 posts
Location
United States of America
Posted 23 October 2015 - 05:28 PM
This seems suspiciously like you're trying to get help with school homework!
It's more of a project furthering my own understanding of what I've been taught… I learned synthetic division last year in Honors Algebra II, and I'm now applying it to polynomials in Honors Pre-Calculus.
In case anyone is wondering, my current progress can be found here ->
http://pastebin.com/zxtG1xBK (this isn't done, I'm going to add imaginary solutions next)Edit: I've now added imaginary solutions! Well, mostly…
Edit #2: Why does negative zero exist in lua? Ewwe. Fixed it.
Edited on 23 October 2015 - 04:08 PM
212 posts
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Somewhere in this dimension... I think.
Posted 23 October 2015 - 10:19 PM
I recently did this and because I am becoming increasingly ahead of my Honors class (the highest they offer here as well) and she knows I program my teacher is starting to challenge me to program a TI-83 to do what we do in class.
Also -0 is a thing I noticed. Also Java sometimes likes to pretend nil == 0 which screws things up…
Edited on 24 October 2015 - 01:54 AM
1522 posts
Location
The Netherlands
Posted 24 October 2015 - 12:34 AM
I recently did this and because I am becoming increasingly ahead of my Honors class (the highest they offer here as well) and she knows I program my teacher is starting to challenge me to program a TI-83 to do what we do in class.
Also -0 is a thing I noticed. Also Java sometimes like to pretend nil == 0 which screws things up…
Add an extra check to work around that:
x = 0
if x and x == 0 then
Blabla
end
My lua is rusty since I was tempting to put a colon for the then, python is my latest interest :P/>
7083 posts
Location
Tasmania (AU)
Posted 24 October 2015 - 01:49 AM
My Java is rusty, but don't certain number types initialise as 0, not nil? Certainly int etc arrays do.
Back in school they had us graphing quadratics; plotting out points for random values of x and guessing what the line between them looked like didn't sit well with me, so instead I wrote a program to draw the graphs properly and printed the output (which didn't sit well with the teacher).
212 posts
Location
Somewhere in this dimension... I think.
Posted 24 October 2015 - 03:56 AM
Pneumaticraft has(had) a drone method that grabbed the fuel, and 0 could be 0, -0, nil, and some insanely small number (both positive and negative) which forced me to use some very interesting system checks.