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 The fit did not converge
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ladyfloflo

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Posted - 08/04/2010 :  3:47:16 PM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic

Operating System: 8.1 SR3 V8.1.34.90

I am trying to fit my data with this known equation but it says that the fit did not converge though the equation did compiled!

P= exp((t-A)/(B+G*(t-A)))/(exp((t-A)/(B+G*(t-A)))+(exp((-H*(t-A))/B)*((1-Ps)/Ps)))

Where P is the dependent variable and t is the independent variable

the parameters are
A,B,G,H, and Ps.

I also don't know where and how to write the script or code for initializing the parameters and/or the script before the fitting
I wish the equation above to have these criteria:

t> A-(B/G)
P=0 for t<=A-(B/G)

the range of P is
P>=0 for all t>=0
For H>0,
P approaches the limit of unity at t becomes very large
At time t=A P=Ps

I also put some initial values for the parameters which I have calculated and still does not converge! What can I do? Or what is the problem???
Any help would be greatly appreciate I can email some data points too.

florence.janvier@gmail.com

larry_lan

China
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Posted - 08/04/2010 :  4:41:14 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Maybe these links can help:

The Fitting Process -- Convergence, Tolerance and Dependencies

Parameter Initialization

General Linear Constraints

Thanks
Larry

Edited by - larry_lan on 08/04/2010 4:42:07 PM
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