[cctbxbb] differential evolution

Peter Zwart PHZwart at lbl.gov
Tue Nov 16 09:13:03 PST 2010


Good point, so I tested it (quickly)

The current implementation needs 748 to minimize a 6D rosenbrock function.

If I update the code to make a temporary population and do not do an
'in place operation', things do not converge under the same settings.

The in place operation of solution vector updates is as far as I
understand in line with the pseudo code found here:

http://en.wikipedia.org/wiki/Differential_evolution

I could have made a mistake of course and if you can show me a code
modification that improves convergence, I'm happy to update the code.

HTH

Peter






On 16 November 2010 08:24, Nikolay Mladenov <nikolay.mladenov at gmail.com> wrote:
> The implementation of the algorithm seems wrong.
> As I understand it, the new generation has to be generated based on
> the old one,
> at which point every member of the old generation is replaced or not
> by its child.
> In the cctbx implementation every member is replaces as soon as it
> gives birth to a better child.
> I am not sure what the implications are but it probably reduces the gene pool.
>
> Nikolay.
> _______________________________________________
> cctbxbb mailing list
> cctbxbb at phenix-online.org
> http://phenix-online.org/mailman/listinfo/cctbxbb
>



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