Interpolating signal from 4 sec to 1 sec?

You should get your desired result by just using the original y with your new time vector xi.

You'll want to use some kind of FFT. Here is a link that explains some methods for time compression (1st Google result btw): http://dspdimension.com/admin/time-pitch-overview.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.