Exponential interpolation

[jp_schwartz]

Hi all!!

I have some points (x,y). When I make a graphic with them, it seems to be an exponential function. I need to calculate some points and I want to use an exponential.

Any clue???
Thanks

[DavidHooper]

does the curve go up or down?

the general eqn is (i think):

y=c * e ^ (ax)

where a and c are constants. and the power is negative if the curve goes down.

[jp_schwartz]

The curve is going up.

Thanks

[jim mcnamara]

Where (ax) would be 1 + the growth rate ie., 4% growth rate would (assuming t = 1) be 1.04

A standard exponential growth rate is written

n = n0 * e ^(r*t) where r= rate of growth, t = time n-0 = initial value , n= value at time t

[fbokker]

If your data is really exponential, you can linearise it with log(y). Then make a linear regression and convert the data back to its original form by calculating e^().

There is also a nice shareware program than can do all these wonders automatically. It's called CurveExpert. you'll find it by typing into some search engine. (however, it works completely different from what I described above).

[jp_schwartz]

Log(y) worked perfectly. Thanks.