help for creating a 2D lookup table .

Question

vvf vvff 2020-2-23

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/507146-help-for-creating-a-2d-lookup-table

评论： vvf vvff 2020-2-25

I want to create a table F so that I could searh values ffrom the table by F(x,y). When I am using the scatteredInterpolant , some points i get inf values. Why it happens ??? for the neighboring values around x y , I got the right values. Thank you so much ！！！！！！！！！！！！！！！！！！！

2 个评论
显示无隐藏无

Cameron B 2020-2-24

We are unable to help unless you post your table and the value(s) you would like to interpolate.

Walter Roberson 2020-2-24

Suppose that you had two points (realmin, 0) and (3*realmin,10) and you ask to interpolate at 2*realmin. Δy = 10, Δx = 2*realmin. Δy/Δx = 5/realmin. But 1/realmin is the largest non-infinite number, so that is 5 times (almost infinity) which is infinity.

Therefore it is possible with locations very close together for interpolation to generate inf even though none of the data is inf or nan.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Walter Roberson 2020-2-24

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/507146-help-for-creating-a-2d-lookup-table#answer_417017

My comment shows how inf can occur for non-infinite values even when examining data inside the region.

However, probably what is happening for you is that you are asking for values at a location outside the maximum triangulation of the scattered data, and you have your interpolation configured to return inf in that case.

More typical is for people to leave interpolation at the default, in which case requesting values outside of the triangulation gets you nan instead of inf.