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Re: Which interpolation?
Posted:
Dec 7, 2012 3:48 PM
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The data presented suggest that the function has a horizontal asymptote at y = 1. If you expect that this is the case, you should try a model that has such an asymptote. E.g., y(x) = 1 + a/x + b/x^2 + ... or y(x) = A*exp(-a*x) + B*exp(-b*x) + ....
Dave
On Friday, December 7, 2012 12:13:12 PM UTC-6, Cristiano wrote:
> From a very slow simulation I got y= f(x):
>
> x y
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> 5 0.8048174
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> 6 0.8194384
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> ...
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> 44 0.9706268
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> 47 0.9724846
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> ...
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> 48765 0.9999756
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> 53765 0.9999776
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>
>
> For every x, I stop the simulation when the confidence interval for y is
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> less than 2,5*10^-6 (with 99% of confidence).
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>
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> I can't calculate all the x's (because the simulation is very slow), so
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> I need to interpolate; for example, I don't have y(45) or y(46).
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>
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> Using the Levenberg-Marquardt Least Squares Fitting, the best equation I
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> found gives an error that is too high (about 10^-4 for small x's).
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>
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> Then I thought to use a cubic spline, but I notice some "fluctuations"
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> on the tails.
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>
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> Should I use LM or spline?
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>
>
> Thanks
>
> Cristiano
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