Interpolation, sigmoid curve

Hi, I'm not very good on matlab, som maybe this is a kind of basic question.

I have 140 values from 140 years of coal mining. There is a maximum limit of how much coal that can be extracted from the mine. My task is to make a prognosis for the next 60 years. It's suppose to look lika a sigmoind curve (an S). I have been able to make a sigmoid curve based on the different values from the years i already have. But my problem is how i'm soppose to interpolate these values into the future?

I have tried to use interp1, but i my result is not that good, it's ether going straight to the roof or below 0. So I would be very grateful for any help that I can get!

Answer 1

[Anton Semechko]

you mean extrapolate into the future, not interpolate ... If you have Optimization Toolbox, you can try fitting the generalized logistic equation to your data (<http://en.wikipedia.org/wiki/Generalised_logistic_curve>) using 'lsqnonlin'

[Anton Semechko]

Also see:

1)http://www.mathworks.com/matlabcentral/fileexchange/31399-fit-logistic-curve-to-a-data-set

2)http://www.mathworks.com/matlabcentral/fileexchange/22547-logreg