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Hi Todor,

On Tue, May 14, 2019 at 3:06 AM Todor Balabanov <todor.balabanov@gmail.com>
wrote:

Hello!

Currently DE implementation in NLPSover has a coefficient called FACTOR:


https://github.com/LibreOffice/core/blob/f4ba484183a1e7b9824f10580d633466c266828f/nlpsolver/ThirdParty/EvolutionarySolver/src/net/adaptivebox/deps/behavior/DEGTBehavior.java#L41


https://github.com/LibreOffice/core/blob/330df37c7e2af0564bcd2de1f171bed4befcc074/nlpsolver/src/com/sun/star/comp/Calc/NLPSolver/DEPSSolverImpl.java#L129

There are some researches about multiple values of the scaling factor:

https://www.sciencedirect.com/science/article/pii/S0020025511000909

My idea is FACTOR to be replaced with two coefficients:

MIN_FACTOR

MAX_FACTOR

We can keep default values for them 0.5, as it is in the source code now.
When we have MIN_FACTOR == MAX_FACTOR the algorithm will believe as it
behaves now. When we have MIN_FACTOR < MAX_FACTOR each time when FACTOR is
needed we can select random uniform value in the range.

What do you think?


It sounds good to me. I don't think many developers have a great knowledge
of nlpsolver so feel free to change that if it actually helps to iterate
towards a solution faster. I'm sure since nlpsolver was written there were
quite some advances in DE and PSO algorithms, which we could incorporate.

All the best,
Todor


Best Regards,
Tomaž Vajngerl

Context


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