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Levenburg Marquardt Questions

DanJoffe
7-Bedrock

Levenburg Marquardt Questions

Can anyone point me to resources to answer the following:
How do you get Lev-Mar to not ignore inequality restrictions in the solve block? It seems to do so with a mind of its own.

Also...in Ver14, it will give complex results in optimization even if the guess values are all reals.

Finally...I've been using Mathcad for years...is there a book you can recommend that might handle these and some other issues not seemingly in the help docs? (Numerical Methods Using Mathcad is not such a book)
2 REPLIES 2
RichardJ
19-Tanzanite
(To:DanJoffe)

On 10/12/2009 5:49:05 PM, djoffe wrote:
>Can anyone point me to
>resources to answer the
>following:
>How do you get Lev-Mar to not
>ignore inequality restrictions
>in the solve block? It seems
>to do so with a mind of its
>own.

The constraints are soft constraints, not hard constraints. The error in the constraint is minimized, along with all the other errors, but not forced to zero. If you want to force it to zero then you need to weight it very heavily. So, for example, instead of "a less than b" use "(a-b)*10^15 less than 0"

>Also...in Ver14, it will give
>complex results in
>optimization even if the guess
>values are all reals.

Please post an example worksheet showing this.

>Finally...I've been using
>Mathcad for years...is there a
>book you can recommend that
>might handle these and some
>other issues not seemingly in
>the help docs? (Numerical
>Methods Using Mathcad is not
>such a book)

No. As far as I know, there isn't one. The best thing to do is ask here.

Richard

>... is there a book you can recommend that might handle these and some other issues not seemingly in the help docs ?<<br> ___________________

I bet my bottom $ you won't find anything more complete than the 80 pages posted yesterday or the day before yesterday. There may be a bug, but undetectable otherwise than in very particular applications. I should add "interpretation" in one of the example ... RemToDo.
w/o ws, can't help. "Save as" 11 as this is the lowest allowable by 14, or just an image because it will have to be recreated.

jmG
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