I have a question about RESAMPLE

when I resample some data,I found that the picture of the start and the end of the resampled-data maybe error,they are shaking,just like drifting

my code:

data2 = resample(data,2,1);

this is the image of the raw data

this is the image of the data after RESAMPLE

U can see some lines are not on the ring.the under part of the ring is the start of the 'data2'. on the right side of the ring is the end of the 'data2'.

this picture is the (1:100) of the 'data2' and 'data' and the red line is the 'data',the blue line is the 'data2'

my question is why can see the fluctuation.

Answer 1

[Youssef Khmou]

This is an interesting remark, however in Documentation, it was mentioned that re-sampling has side effect because of filtering process, the edges of the re sampled vector are deviated.

[Can]

Thank you very much for your answer. how to avoid the deviation?

[Youssef Khmou]

you can study the variation of that deviation with a fourth parameter n, resample(data,2,1,n) the default value is 10, try with zero. But there no definite answer on how to avoid the error.

Remark : you want to re-sample the data with double, you can use the function interp, like in this example :

t=[1e-4:0.1:2*pi]';
data=[cos(t),sin(t)];
x2=interp(data(:,1),2);
y2=interp(data(:,2),2);
figure; plot(data(:,1),data(:,2),'k+');
hold on
plot(x2,y2,'r')
legend(' original','re sampled');