[daip] RMSD bug found

[Glenn Morrison]

Yo Eric,



When I use OPTYPE ='HIST' in RMSD and have the input file as seen  
below I get the following "quantized" flux plot from IMEAN:



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However, then I have OPTYPE ='ROBS' the IMEAN plot looks fine as seen  
below:


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I ran the midnight job today before I ran RMSD. Both results we're run  
on an Mac pro mac-tel (AIPS version 31DEC08). You can pull over the  
radio map from:


http://www.cfht.hawaii.edu/~morrison/x1GOODSN/Eric/

I've been running RMSD on this map.  IMSIZE=100,-1 for both cases.



  -Thanks

--Glenn






AIPS 3: RMSD      Creates the image of RMS at each velocity plane.
AIPS 3: Adverbs     Values                 Comments
AIPS 3: ----------------------------------------------------------------
AIPS 3: INNAME     'GOODSNV1001'           Input image name (name)
AIPS 3: INCLASS    'FLATN'                 Input image name (class)
AIPS 3: INSEQ         1                    Input image name (seq. #)
AIPS 3: INDISK        1                    Input image disk unit #
AIPS 3: OUTNAME    ' '                     Output image name (name)
AIPS 3: OUTCLASS   'RMS1.7'                Output image name (class)
AIPS 3: OUTSEQ        0                    Output image name (seq. #)
AIPS 3: OUTDISK       1                    Output image disk unit #.
AIPS 3: BLC        *all 0                  Bottom left corner of input
AIPS 3: TRC        *all 0                  Top right corner of input
AIPS 3: IMSIZE      100          -1        Size of the box used to
AIPS 3:                                    calculate rms, in pixels
AIPS 3:                                    IMSIZE(2)=-1 => the circle
AIPS 3:                                    of diameter=IMSIZE(1)is used
AIPS 3: OPCODE     'RMS'                   'RMS ', 'MEAN', or 'BLAN'
AIPS 3:                                    (see help), '    ' => 'RMS '
AIPS 3: OPTYPE     'ROBS'                  'ROBS', 'HIST' <<<<<<  I  
ONLY change this!!!!
AIPS 3:                                    (see help), '    ' => 'ROBS'
AIPS 3: SCALR1        1                    Data<SCALR1*RMS are replaced
AIPS 3:                                    by blank (OPCODE='BLAN')
AIPS 3: SCALR2        0                    >0 =>
AIPS 3:                                     ABS(DATA) < SCALR2*RMS
AIPS 3:                                     are replaced by blank
AIPS 3:                                     (OPCODE='BLAN')
AIPS 3:                                    <0 =>
AIPS 3:                                     ABS(DATA) > ABS(SCALR2)*RMS
AIPS 3:                                     are replaced by blank
AIPS 2:                                     (OPCODE='BLAN')
AIPS 2:                                    0 => no blanking
AIPS 2: SCALR3        0                    Number of RMS used at each
AIPS 2:                                    iteration calculating final
AIPS 2:                                    RMS.  0 => 3
AIPS 2: FLUX          0                    Data with RMS>FLUX
AIPS 2:                                     are replaced by blank
AIPS 2:                                     (OPCODE='BLAN')
AIPS 2:                                    0 => no blanking
AIPS 2: XINC          1                    Increment at X to calculate
AIPS 2:                                    RMS, in pixels
AIPS 2: YINC          1                    Increment at Y to calculate
AIPS 2:                                    RMS, in pixels
AIPS 2:                                    The intermediate points are
AIPS 2:                                    calculated by interpolation


On Jul 21, 2008, at 2:53 PM, Frazer Owen wrote:

>
>   There is another issue which may be important which Eric pointed  
> out if you use the 16 bit option
> for FITTP. The FITS image is scaled to fit between the maximum and  
> minimum values. If the maximum is
> very large while most of the data are very small then the small  
> values will be quantized.  It seems possible that
> RMSD could produce a very large number near the edge of the image.  
> If so that might produce the
> quantized result. You should check the minimum and maximum after you  
> run RMSD to make sure
> there are no very large numbers and that you are not using the 16bit  
> option for FITTP.
>
> ---Frazer
>
>
>
>
> Glenn Morrison wrote:
>> The RMSD map I sent you was not made using HIST.
>>
>> also Frazer suggests IMSIZE=100,-1 to get a circular region. I  
>> would not use any option but 'HIST'.
>>
>> Not sure what problems Edo has had. Is he using the latest version  
>> of AIPS?
>>
>> -Thanks
>>
>> --Glenn
>>
>>
>> On Jul 21, 2008, at 1:02 PM, Rob Ivison wrote:
>>
>>>> --Big thanks to Edo (what is his email address??) for finding  
>>>> this!!!!
>>>
>>> Edo is ibar at roe.ac.uk and he's a real gem. not sure i've ever  
>>> found anyone quite so thorough. he makes Biggs look sloppy, and  
>>> when i first met Biggs i thought he was beyond retentive.
>>>
>>> Edo informed me today that a noise map made using the HIST option  
>>> in RMSD plays havoc with SAD, amongst lots of other little  
>>> snippets of wisdom. sometimes it feels like he's supervising me.
>>>
>>> cheers,
>>>
>>> Rob