# How do you derive a function that describes a series?

It's been a really long time since I've done calculus or any other kind of math beyond tip calculation. I was given a spreadsheet that calculates and plots a growth curve over time based on a handful of inputs. It goes out for one year. I'd like to be able to make educated (though not necessarily precise) predictions of values along the curve for any amount of time, but if I can avoid it, I'd rather not just extend the length of the spreadsheet. The series is nonlinear, the first values look like this:

540 545 561 599 672 780 904 1,016 1,098 1,151 1,193 1,238 1,297 1,367 1,444

THat's the first ten days of the year, given a 'seed' value of 500 (which of course is one of the variables).

Like I said, I don't need it to be super accurate, just generally describe the slope over time, I just don't know where to even begin figuring out the equation.

Thanks, Paul

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Point of vocabulary: you probably mean "sequence", not "series". Also, the set of data you gave has fifteen elements for ten days, i.e. more than one data point per day: is that accurate? If so, is the data generated on a regular time interval (that interval being, I guess, one data point every 16 hours)? – Alex Basson Jan 2 '11 at 17:31
Problem is "time series" is frequently used to refer to a sequence indexed by time. – Raskolnikov Jan 2 '11 at 19:37
No, sorry, headspace and timing error. It's one data point per day. – Paul Jan 3 '11 at 2:23