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From Ole Ersoy <>
Subject Re: [math] ConvergenceChecker
Date Mon, 08 Feb 2016 21:18:37 GMT
Hi Evan,

On 02/08/2016 08:10 AM, Evan Ward wrote:
> Hi Ole,
> On 02/05/2016 06:40 PM, Ole Ersoy wrote:
>> On 02/05/2016 04:42 PM, Evan Ward wrote:
>>> Yes, I use it. In some cases it is useful to watch the RMS residuals
>> So if it were modularized and supported logging then this might
>> satisfy the same requirement?
> I'm not sure if I understand what you mean by logging,
One of the reasons I'm refactoring and modularizing (Making it a standalone jar) the LM optimizer
is that I'd like to be able to watch certain steps in action, in the event that issues crop
up.  So since you mentioned that you were 'watching' the residuals I assumed it had a similar
purpose that aligned well with logging.

[...]  Has there ever been a case where the 'standard' convergence approach
has been insufficient?

> I think this depends on what is included in the standard convergence
> checker. I think 90% of uses could be handled by watching the change in
> cost or state. I like the option of specifying my own condition, so I
> can control exactly when the algorithm stops.
If it's useful to you then I'm sure it's useful to other as well. Just want to make sure that
you definitely need more flexibility than what comes with relaxing or tightening the relative
and absolute tolerance parameters.  I'm also curious whether the cases that you do need flexibility
for could be parameterized in such a way that it makes it simpler to write up to user documentation?

>> Also could you please look at this:
>>      public static LeastSquaresProblem countEvaluations(final
>> LeastSquaresProblem problem,
>>                                                         final
>> Incrementor counter) {
>>          return new LeastSquaresAdapter(problem) {
>>              /** {@inheritDoc} */
>>              @Override
>>              public Evaluation evaluate(final RealVector point) {
>>                  counter.incrementCount();
>>                  return super.evaluate(point);
>>              }
>>              // Delegate the rest.
>>          };
>>      }
>> Should this exist?
> Looks useful for counting evaluations, but I think all of the LS
> optimizers already do this. Anyone have a use case for countEvaluations?
I think you are right.  I think it's code that was accidentally left in...Anyone...?


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