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PEST and initial Marquardt lambda value


Bernard
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Hi All,

I am tyring to calibrate a steady-sate MODFLOW model using PEST in GMS 8.0. Does anyone know where can the initial Marquardt lambda (RLAMBDA1) value be specified? I have performed an initial (unsuccessful) run and it seems that the default value is set 0.01. However, I would like to increase this value somewhere in between 1 to 10. Yet, I can't seem to find any input dialog for this option.

Any help is much appreciated!

Cheers

Bernard

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Currently, there is no way to directly specify this value in GMS. Based on the advice of John Doherty, the value of RLAMBDA1 is set to 10.0 if the user is not using SVD and set to 0.01 if the user is using SVD. If you would like to change the value of RLAMBDA1 the do the following.

1. Save your project. A file is saved in the MODFLOW folder called *.m2p. This is the mf2pest file.

2. Open the m2p file in a text editor and change the value listed for RLAMBDA1. Save the file.

3. Now from GMS you can run PEST and it will use the value specified in the m2p file.

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