[R] Curve fitting tutorial / clue stick?

[Allen S. Rout]

Working through the R archives and webspace, I've mostly proved to myself that
I don't know enough about what statisticians call "Curve Fitting" to even
begin translating the basics.


I'm a sysadmin, and have collected a variety of measurements of my systems,
and I can draw pretty pictures in R showing what has happened.  People are
happy, customers feel empowered.  Whee!


Now, I want to take my corpus of data and make a prediction based on it; In
statistics-moron speak, I want to draw a line or a simple curve across my
extant graph, and figure out where the predictive curve passes threshold 'T',
and then graph that too.


I thought I'd be telling R something like:  

- I think this is exponential.  Here's the data.  Give me the best function
  you can come up with, and tell me "how good" the fit is.

- I think this is quadratic.  Here's the data.  Give me the best function
  you can come up with, and tell me "how good" the fit is.



Can someone point me at a spot in the docs which might be suitable for my
level of ignorance?  


- Allen S. Rout