Finding approximate y values for corresponding x values in matlab

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Oila R
Oila R 2019-5-31
回答： Santiago Alcantara 2022-2-10
Suppose I have a graph (formed from data) that has x and y values, but it is not analytic (so not continuous). I need to find a way such that for any x value, matlab will find the closest x value on the graph and give me the corresponding y value. Any ideas?
for example:
x y
1 2
2 5
3 8
4 13
5 23
6 49
So say that is my function, and I want to find the y value that corrisponds to x = 3.1 or 5.2, etc. The data is weird so I cant to a trivial linear approximation or something like that for the whole graph.

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采纳的回答

Fangjun Jiang
Fangjun Jiang 2019-5-31
interp1(x,y,3.1,'nearest')
  2 个评论
Aleksandr Shmidt
Aleksandr Shmidt 2020-8-30
just ran the snip in the code, 'nearest' will aproximate to the closest value in the data instead of finding value by the trend
Fangjun Jiang
Fangjun Jiang 2020-8-31
That is what the OP wanted. "find the closest x value on the graph and give me the corresponding y value".

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更多回答（1 个）

Santiago Alcantara
Santiago Alcantara 2022-2-10
A first aproach that you can use is the function "polyxpoly"( https://es.mathworks.com/help/map/ref/polyxpoly.html).
Another aproach is:
[val_1,idx_1]=min(abs(x-y))
This is usefull when the values are not exact values. You will find the minimun difference near to cero and exactly index to play with.

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