[evlatests] Integer zeros slipping through?

[Eric Greisen]

Rick Perley wrote:
>     In continuing to troll through the 3C273 data taken a couple weeks 
> back, I find a curious problem that I thought had been dealt with long 
> ago. 
> 
>     One some of the scans, there are what appear to be integer zeros, on 
> some baselines.  It's hard to prove these are pure integer zeros -- I 
> can only state for sure that these numbers are much less than 1e-20. 
>     The unique feature of these zeros is that they are all at the end of 
> the scans.  None in the middle, and none at the start. 
>    
>     I had thought that the BDFin program automatically stripped out 
> integer zeros.  Is this no longer so?  Or perhaps my 'integer zeros' are 
> not quite integer zero? 
> 
>   
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The initial data set read in by BDFIn indeed has a lot of pure zeros in 
the last time sample of some of the scans.  But they are not all zero - 
some spectral windows appear to be populated with real values while 
others are not.  Which spectral windows are zero and which not varies 
with baseline.

Rick's deeper problems are, however, an AIPS bug now being fixed.  The 
output of BDFIn had weight 0 with all the pure zeros so they would not 
affect the analysis.  Unfortunately, a relatively new option in TYAPL, 
caused the 0.0 weights to become positive which resulted in Rick's 
analysis being corrupted by the zeros after application of the SysPower 
tables by TYAPL.

Eric Greisen