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BadFixes.txt
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BadFixes.txt
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ML doesn't always converge, especially if the problem geometry is
pretty bad. All the receivers off to one side of the
transmitter, and with bad standard deviations, for example.
Bad fixes: seed numbers
./testlsDF_proj --seed 1242957545 106d59\'W 34d50\'N < receivers6_sloppy
./testlsDF_proj --seed 1242981211 106d14\'W 35d50\'N < receivers6_sloppy
Both of these let the ML fix go off to never-never land. I was
successful at getting the first to converge with a little help
from Nelder-Mead, but not the second. Must try harder.
In both cases, the problem is that the cost function is very,
very flat for a huge part of the space, and very, very steep near
the LS fix. The initial line search down the steepest-descents
direction takes us way out there from the LS fix trying to find
the minimum in that direction, and it shoots us so far out that
we're in a vast, very flat area where CG has no hope of ever finding the
real minimum anymore.
There must be a way to detect this kind of failure mode and nip
it in the bud, perhaps by not trying to find the real minimum in
the initial few directions, but settling for 'better than where
we started'