[Insight-developers] New GetStopConditionDescription() for itkOptimizers

[Luis Ibanez]

Bill,

This sounds like a very useful feature to have.

The only question I have at this point is:

What should the method return if it is called before
the optimizer stops ?

Maybe something like
"Still Running"  ?


       Luis


-------------------------------------
On Wed, Jun 10, 2009 at 12:53 PM, Bill Lorensen <bill.lorensen at gmail.com>wrote:

> Folks,
>
> I'd like to add a new method to itkOptimizer and its subclasses. The new
> method,
>
> GetStopConditionDescription() returns a const string that describes
> the stop condition of the optimizers. Currently, each optimizer
> returns a StopCondition that is an enum. The new method contains
> useful information depending on the optimizer. The itkOptimizer base
> class method returns "Optimizer did not provide a stop condition
> description".
>
> I instrumented the Examples/Registration examples to report the stop
> condition description. Here is a sampling:
>
> GradientDescentOptimizer: Maximum number of iterations (200) exceeded.
> RegularStepGradientDescentOptimizer: Step too small after 17
> iterations. Current step (0.0078125) is less than minimum step (0.01).
> RegularStepGradientDescentOptimizer: Gradient magnitude tolerance met
> after 43 iterations. Gradient magnitude (7.75281e-05) is less than
> gradient magnitude tolerance (0.0001).
> RegularStepGradientDescentOptimizer: Maximum number of iterations
> (200) exceeded.
> RegularStepGradientDescentOptimizer: Step too small after 22
> iterations. Current step (0.00078125) is less than minimum step
> (0.001).
> GradientDescentOptimizer: Maximum number of iterations (200) exceeded.
> AmoebaOptimizer: Both parameters convergence tolerance (0.25) and
> function convergence tolerance (0.001) have been met in 27 iterations.
> AmoebaOptimizer: Both parameters convergence tolerance (0.1) and
> function convergence tolerance (0.001) have been met in 53 iterations.
> LBFGSOptimizer: Failure
> LBFGSBOptimizer: Function tolerance reached after 32 iterations. The
> relative reduction of the cost function <= 2.22045e-09 =
> CostFunctionConvergenceFactor (1e+07) * machine precision
> (2.22045e-16).
> LBFGSBOptimizer: Function tolerance reached after 29 iterations. The
> relative reduction of the cost function <= 2.22045e-09 =
> CostFunctionConvergenceFactor (1e+07) * machine precision
> (2.22045e-16).
>
> Some need more work, e.g. LBFGSOptimizer.
>
> Bill
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