Can interp1 function be used when the time interval of data isn't uniform?

Question

Swasti Khuntia 2012-8-20

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/46330-can-interp1-function-be-used-when-the-time-interval-of-data-isn-t-uniform

In the interp1 function, yi = interp1(x,Y,xi,method), I have x as time vector with non-uniform interval. But the length of x and Y vectors are same. Can I use the interp1 function to interpolate the data?

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

José-Luis 2012-8-20

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/46330-can-interp1-function-be-used-when-the-time-interval-of-data-isn-t-uniform#answer_56693

Yes, but the longer your interval the more uncertain your results.

4 个评论
显示 2更早的评论隐藏 2更早的评论

Walter Roberson 2012-8-20

All line segments have the same number of mathematical points ("the infinity of real numbers"), so the potential mathematical variability over any line segment is the same as for any other line segments. One cannot generalize about uncertainty over different intervals without knowing the process responsible for the variability.

As a quick example, the uncertainty of the sinc() function over short intervals near 0 is much greater than the uncertainty over long intervals at large x. Larger intervals are not always more uncertain.

José-Luis 2012-8-20

编辑：José-Luis 2012-8-20

I see your point. It depends on what you are modelling or measuring of course. However, even if you (think) you know your process, there is the problem of unknown unknowns. Unless the system is a very simple one, things will arise that will surprise you, therefore the more uncertainty the larger the interval. And if you are sure of how it works, then why would you need to measure? It all depends on your perspective (as always), and it is an interesting discussion, but maybe overkill for the question of the op.

请先登录，再进行评论。

Answer 2

Matt Fig 2012-8-20

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/46330-can-interp1-function-be-used-when-the-time-interval-of-data-isn-t-uniform#answer_56707

在 MATLAB Online 中打开

When I have a question like this, I just do a little experiment.

x = sort(rand(1,30)*2*pi); % Non-uniform data
y = sin(x);  % Underlying function
xi = 0:.25:2*pi;  % Interpolation points
yi = interp1(x,y,xi,'spline');
plot(x,y,'*r',xi,yi,'b')