2009/9/23 Malcolm J. Currie <[log in to unmask]>:
>> Malcolm Currie is looking into it, (see an email he sent below), so I
>> guess it is best to wait to see what the explanation was.
>
> Regressing to use the exclude most-likely candidate fix from last December,
> still does not generate silly fits. It is only the masking that's affected
> in that fewer pixels are masked with the bug. I've not been able to
> reproduce the problem with the development code and some older versions of
> MFITTREND subroutines. I suppose I could download the lehuakona source,
> rebuild everything, and debug over again. That would start with the known
> instance, and might reveal the extent of the damage.
>
>> One critical question for NGLS is how much does the occurrence of the bad
>> fitting bug depend on the input .sdf and the command line parameters of
>> mfittrend. This is probably easier to answer by looking at the code
>> differences in the KAPPA versions rather than repeated testing on lots of
>> cubes.
>
> It doesn't appear so. The effect of some bugs isn't predictable and
> surprising results can ensue. Sometimes coming back to code, I'll find a
> bug and wonder how the code ever worked. There are compiler differences
> too. Given there was a fix made somewhere yet it's only been noticed for
> the second time after 9 months suggests that it's is a restrictive set of
> parameter values, and my gut feeling (based upon the evidence) is that
> method=global is the key determinant. Now perhaps some data are unaffected,
> but if we can automate the re-reductions we might as well address all the
> processed cubes.
>
> As a compromise, could Jamie please try further tests with the known problem
> dataset, using all the MFITTREND parameter settings invoked during the NGLS
> reductions. Are there any other problem fits other than when method=global?
> I can't do this because I don't know how the NGLS data have been reduced.
>
> I think better use of my time would be to help address how to re-reduce
> Christine's data. First can the scale of the problem be assessed by running
> HISLIST on the reduced data
You may find "provshow fred history=yes" useful - it displays history
for *all* ancestor NDFs that were used in the creation of "fred.sdf".
By comparison, "hislist fred" just tells you about the *primary*
ancestor NDFs.
David.
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