Curve fitting

Hello /prog/
I've been talking to Xarn about curve fitting and I wanted to know your opinions on this as well.
Is anyone here familiar with curve fitting?
http://bbs.readsicp.org/kareha.pl/1468337795/

>>7
I know about frequency analysis and how it can be used to break caesar cipher, but I don't know what's selective deconvolution or how this all relates to the topic of fitting a curve to some general data.

Wait!
There's more than 1 thing called frequency analysis.
https://en.wikipedia.org/wiki/Frequency_analysis_%28disambiguation%29
Which one are you talking about?

And no, I don't know what it is.
Can you explain how it's useful for curve fitting?