Preconditioner or preconditioning for Constrained Nonlinear Optimization VI and Downhill Simplex nD VI

Dear users,
do optimisation algorithms, such as the Constrained Nonlinear Optimization VI and the Downhill Simplex nD VI, use internal preconditioning or does the user have to do it on their own? There is no note or word in the help about (pre)scaling the functions or the variables. On the other hand, there is no word about any nonnecessity to do so.
Cheers,

Hello ghighuphu,
the VI's "just" do their algorithm, so they aren't using internal preconditioning. The user have to do this by himself.
Best regards

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帖子被myafu在12-22-2006 01:33 AM时编辑过了

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Go to Solution.

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sequenceToRateError.vi ‏18 KB
Times.ctl ‏5 KB

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Here is the error message
Joy
Solved!
Go to Solution.
Attachments:
LN-fitting.vi ‏21 KB
LN-fittingmodel.vi ‏18 KB
Book2.txt ‏1 KB

Thanks for reply. whitenoiz
Actually I have more than 100 XY data set to test my vi. Some of the data set can be fit flawlessly. And the best fit parameters obtained from my vi are exactly the same as those from other analytical software, like OriginLab. In this case, I know my vi is valid. And in this scenario, I also found 1+b(x-xc)/a is always larger than zero with the best fit parameters (a and b). However, for certain XY data set, the error message will pop up if I use LV built-in vi, but I still can obtain the best fit parameters with OriginLab. And then I realized that error message always pops up as 1+b(x-xc)/a is less than zero, which it means to me that as LV built-in vi handles this type mathematical function, this built-in vi will encounter some difficulties.
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Constrained Nonlinear Curve Fit VI: Termination Revisited (LabVIEW 8.5)

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-Jim

Need examples for non-linear optimization

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www.sbrickey.com
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Preconditioner or preconditioning for Constrained Nonlinear Optimization VI and Downhill Simplex nD VI

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