operations on (X,Y) series

[Frederic Parrenin <parrenin ujf-grenoble fr>]

Dear gnumeric fans,

I would like to do various operations on (x_i,y_i) series in gnumeric,
e.g.:
- resampling, by simple interpolation or by integration, with a linear,
spline or staircase interpolant
- filtring by various methods
- smoothing by various methods
- fitting
- principal components
- Periodogram
- etc.

I searched in the gnumeric menus by the only things I found were linear
regressions and smoothings (by moving average and by exponentional).

Did I miss something? 
(for example, a tool to resample would be really needed)

If not, I will try to write a plugin for gnumeric.
Is there a documentation on how to write a plugin for gnumeric?
In which languages is it possible to write a plugin? (is it possible in
python?)
Do you have suggestions for that?

Best regards,

               Frédéric