Fourier transforming from x and y columns

I have a function; y = f(x) in a text file column 1 = x, column 2 = y. I have imported the columns and declared them as x and y respectively. This is how the function looks like when I put plot(x,y). So, back to the question, how do I Fourier-transform this function? Thank you!

Answer 1

[Thorsten]

 u = fft(y);

[Walter Roberson]

No, that would only work if the x were at consistent intervals.

Answer 2

[Walter Roberson]

http://www.mathworks.com/matlabcentral/fileexchange/25135-nufft--nfft--usfft