Running PEST

When you have set up the inputs and
outputs in your model that will be used by PEST, you can go the the Actions
tab in the PEST interface tool notebook and try to run it.

The run length from the run control
will be used unless you alter it in the input box. If you do not select the
checkbox in the Predictive analysis
section, a simple parameter estimation will be done. Note that if all your
outputs are time series, the run length will be up to the last time series
value and the entry box for it will have no effect.

A PEST run can be controlled in the same way as a model run
" it can start, stop or pause. The progress bar is inaccurate
because it is impossible to tell in advance how many model runs PEST will
need before it converges on the best parameters. It just shows what
proportion has been done of the maximum number of runs specified in the
settings.

While PEST is running you will see the run control values and progress
bar update during each run. You will also see statistics about the run
appear in the execution monitor box of the Actions tab. The text box in the
execution monitor displays PEST's output to the command line, which is
useful in case it should fail for any reason.

Simile's other helper tools are also updated while PEST runs. This means
that if you have a slider tool for the variable parameters which are under
PEST's control, you can watch them update as PEST adjusts them to optimize
the outputs. However you may not want the tools to be updated, as they may
slow down execution, and the plotter will show a separate trace for each
run. To turn off all helper updates, set the 'Display interval' entry in
the Run Control dialogue to zero.
Alternatively you can set it to an interval longer than the run length, so
the helpers (including sliders) will only be updated at the start of each
run.

PEST produces a selection of output files during a run. These are kept
in Simile's temporary directory. When PEST has finished running, you can
save any of these in a permanent directory using the 'Save a PEST file...'
button. Each pest file has a different extension; use the extension chooser
in the save dialogue to choose the file you want, and enter the name you
want to give it.

If PEST fails to converge on a good set of parameters, you can adjust
its settings. The global settings, such as NOPTMAX to control the maximum
allowed number of optimization stages, are on the Settings tab. Settings
related to each input or output, such as PARCHGLIM which affects how the
maximum change of an input value on a single step is applied, can be edited
in a context menu for that input or output " right click (ctrl
click on Mac) on the input or output field to bring this menu up. The
labels on these entries correspond to the names of the settings as
described in the PEST manual, which you should refer to when adjusting
them.

In: Contents >> Running
models >> PEST