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> 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 and search for those NDFs that used lehuakona (KAPPA 1.9-11) and mfittrend method=global? As Frossie says, with ORAC-DR it should be possible to re-reduce data quickly, unless there was a significant manual interaction. While trying to find more about NGLS, I came across the Wilson et al. paper on molecular gas in four Virgo spirals. It dismayed me to see that the software (CUPID and KAPPA should be capitals BTW), just had footnotes rather than proper citations. Programmers have careers to worry about too. In future papers please consider this. For CUPID there's the Berry, D.S. et al., 2007, ASP Conf Series 376, Astronomical Data Analysis Software and Systems XVI, 425. For KAPPA, I suggest a URL to SUN/95 pointing to JAC's copy. Malcolm