Talk:Interpolation

Support

Related to the above (but simpler and more relevant), there is no discussion of support on this page. In one-dimensional interpolation, the difference between interpolation and extrapolation is simple. However, in multivariate statistics what is "in" and what is "out" may not be clear naievely. For example, if you fit a plane to $f(x,y)$ where all your $(x,y)$ pairs fall in an ellipse close to $y=x$ and all with $(x,y)\in [0,1]$ it is easy to decide that $f(2,2)$ is extrapolation, but it may be easy to overlook the fact that $f(0.75,0.25)$ is also extrapolation. It is clear if you look at a scatter plot with no coordinate system, or if you transform the problem with PCA, but naievely the fact that $0.75\in [0,1]$ and $0.25\in [0,1]$ throws people off. With that in mind, this page should mention this subtle corner case of when what looks like interpolation is actually extrapolation. In this case, the convex hull of the $(x,y)$ points would define one version of support; something related to Mahalonobis distance would define another. —Ben FrantzDale (talk) 15:07, 30 August 2010 (UTC)

I fully agree, the idea is not clear in higher dimensions. I think interpolation is not the opposite to extrapolation, though. You can extrapolate with an interpolant! See my entry Talk:Interpolation#Doesn.27t_explicit_the_relation_to_the_given_data. Kakila (talk) 16:18, 16 February 2017 (UTC)

Doesn't explicit the relation to the given data

As I see it, main point of interpolation is to generate a function that goes exactly through the given data, i.e. opposite to Smoothing. Of course one will use the obtained function to evaluate outside of the range of the given data (yaiks, Extrapolation does the same!), but the point of interpolation is that we want to recover the given data exactly. Also in higher dimensions "within the range" doesn't have an unique meaning, except maybe in convex data sets. I have seen so much confusion emerging from this jargon that I decided to write a blog entry with a new term: "intrapolation". Kakila (talk) 16:14, 16 February 2017 (UTC)

Restructure article

I propose to split article into two sections:

• Estimation of the interpolation function
• Interpolation between set of numbers

Currently the article weirdly starts by discussing the first topic.--AXONOV (talk) ⚑ 13:23, 1 July 2021 (UTC)

A video that better idealize the heading

?)Add video 183.82.163.191 (talk) 09:44, 13 November 2022 (UTC)

India Education Program course assignment

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The above message was substituted from {{IEP assignment}} by PrimeBOT (talk) on 19:54, 1 February 2023 (UTC)