- b = 1 and d = 3
- b = 2 and d = 2
- b = 4 and d = 1
- b = 8 and d = 0
Determining Constants of Best Fit Curve
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I have a dataset (x,y) that I would like to fit a curve to. The curve must be of the form:
y = a + b*c^d*x^e
where a,b,c,d,e are constants and constants a and c are known.
Is there a way to numerically determine these constants in matlab?
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Accepted Answer
Steven Lord
on 6 Nov 2015
No. You can't decouple b and d: consider that (b)*c^(d) and (b*c)*c^(d-1) are the exact same value. So let's say you determine for your particular data set that b*c^d is 8 and you know c is 2. We could have (assuming b and d were restricted to take on only nonnegative integer values.)
All of those result in a value for b*c^d of 8. Which solution is the "correct" solution? Without other information, they all are.
If you want to try to determine e and b*c^d search the documentation for "curve fitting" and you'll find descriptions of many different tools that you can use for this application.
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