finding the equation of a polynomial given its graph

Question

I have a graph of polynomial and I would like to know how to determine its equation.

Please, this isn't homework. What I'd like to do is actually reproduce this graph.

Thanks.

graph

Are you given points on the graph? – RDizzl3 Apr 12 '14 at 21:11 — RDizzl3, Apr 12 '14 at 21:11
@RDizzl3 The only points I know are the x intercepts. – Jay Apr 12 '14 at 21:37 — Jay, Apr 12 '14 at 21:37

score 1 · Answer 1 · answered Apr 12 '14 at 21:15

Assuming you have the points on the graph, either use newton's polynomial interpolation, or lagrange polynomial interpolation, I believe also if you make an approximation of the same (polynomial) degree, as your graph, then you should get a very accurate (if not exact) approximation.

Also the graph you have presented looks like a 6th order polynomial, so I would go with a 6th order interpolation.

score 1 · Answer 2 · answered Apr 14 '14 at 00:29

1

(x+4)*(x+2)*x*(x-2)*(x-4)*(x-6)*((x-8)**2+0.5**2)

comes close and has a nice structure.

answered Apr 14 '14 at 00:29

Lutz Lehmann

126,666

finding the equation of a polynomial given its graph

2 Answers2