Interpolate uniform to non-uniform sampling, artifacts with spline

Hi, I have to resample uniformly sampled data to a non-uniform sampling. I use the spline function for this, and if the sample shift does not exceed a threshold, this works fine. But if it does, I get artifacts and the data gets messed up. Are there any better ways to achieve this? Thank you

[Image Analyst]

Post your data and what you've tried so far. I don't see any reason why it should behave as you say. Also include screenshots. And define what a "sample shift" is, and how you are coming up with the non-uniform x values.

[John D'Errico]

The crystal ball is so foggy. You have told us only that you are doing something wrong. However, the good news is my crystal ball does tell me that you will come into a considerable sum of money in the near future. Hmm. Or maybe it tells me that you will meet a monkey soon. :)

Seriously, you need to give some details if you expect any intelligent help.