Interpolate between specific values in a data set

2022 5 8
1 个回答
回答已采纳
更新时间：2022 5 8
68 次查看（30 天）

0 个投票

I am having trouble trying to figure out how to interpolate between specific y values for 2 given x values from excel.
For example in excel:
X Y
1 0.2
2.2 0.35
3 0.4
4 0.5
then given an X value of 3.5 from a matlab output I would like to find the corresponding Y value, in this case it would be 0.45. Then store that and use that in the future. I am not sure how to search for where 3.5 would sit within the X column and then find the surrounding values to do the interpolation.

请先登录，再回答此问题。

 采纳的回答

the cyclist
the cyclist 2022-5-8
编辑：the cyclist 2022-5-8
Ran in:

0 个投票

Ran in:
You can use the interp1 function to do interpolation.
x = [1, 2.2, 3, 4];
y = [0.2, 0.35, 0.4, 0.5];
x0 = 3.5;
y0 = interp1(x,y,x0)
y0 = 0.4500

4 个评论
显示 2更早的评论 隐藏 2更早的评论

Reece Smith
Reece Smith 2022-5-8
oh okay thanks, didn't realise it was as simple as that. I implemented it into the code but the values seem to be slightly off incomparison to my hand calculated values which I have double checked are right, I am guessing this is just since interp1 does it a little different?
Torsten
Torsten 2022-5-8
编辑：Torsten 2022-5-8
0.45 = 0.4 + (0.5-0.4)/(4-3) * (4-3.5)
Linear interpolation between (3/0.4) and (4/0.5).
What's your method ?
Reece Smith
Reece Smith 2022-5-8
Yea its the one you just put. I am comparing my answers to someone elses interpolations so maybe they just rounded earlier and made it slightly different.
the cyclist
the cyclist 2022-5-8
@Reece Smith, if you can upload an example of the data and code that give a different result from what you expect, we could try to help you understand the difference.

请先登录，再进行评论。

更多回答（0 个）

类别

在 帮助中心 和 File Exchange 中查找有关 Interpolation 的更多信息

产品

版本

R2020b

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by