[daip] FLATN in AIPS08

[Eric Greisen]

Ruta Kale wrote:
> Hello,
> I have installed aips08 in linux(CentOS).
> i ran imagr and created an image with 59 facets.i am using FLATN to
> put together these facets.FLATN is running extremely slowly(more than 5 
> times slower) compared to
> what it used to in DEC05 version.i am copying the FLATN inputs :
> AIPS 1: FLATN: Re-grid multiple fields and pointings to one image
> AIPS 1: Adverbs     Values                 Comments
> AIPS 1: ----------------------------------------------------------------
> AIPS 1:                                    Input images
> AIPS 1: INNAME     '150RR70AS'                Image name (name)
> AIPS 1: INCLASS    'RIM001'                   Image name (class)
> AIPS 1: INSEQ         1                       Image name (seq. #)
> AIPS 1: INDISK        3                       Image disk drive #
> AIPS 1: NFIELD       59                    Max number of fields per
> AIPS 1:                                       pointing
> AIPS 1: NMAPS         1                    Number of pointings
> AIPS 1:                                    Output image
> AIPS 1: OUTNAME    ' '                        Image name (name)
> AIPS 1: OUTCLASS   ' '                        Image name (class)
> AIPS 1: OUTSEQ        0                       Image name (seq. #)
> AIPS 1: OUTDISK       2                       Image disk drive #
> AIPS 1: IMSIZE     8192        8192        Output image size in pixels
> AIPS 1: COORDINA   *all 0                  Central pixel coordinate
> AIPS 1:                                    all 0 => use observed
> AIPS 1: COOTYPE    ' '                     Desired projection type
> AIPS 1: COOINC        0           0        Desired coordinate increment
> AIPS 1: COOREF        0           0        Desired reference pixel
> AIPS 1: ROTATE        0                    Rotation to be used (deg)
> AIPS 1: REWEIGHT      0           0        (1) Interpolation halfwidth
> AIPS 1:                                    (2) Minimum fraction of good
> AIPS 1:                                        pixels required (0->1/3)
> AIPS 1: WEIGHTIT      0                    Weight image down by WEIGHTIT
> AIPS 1:                                    times radius from center in "
> AIPS 1: EDGSKP        0                    Skip pixels around the edges
> AIPS 1: OPTYPE     ' '                     For mosaics only (NMAPS>1)
> AIPS 1:                                    compute and output expected
> AIPS 1:                                    noise ('NOIS') or weight
> AIPS 1:                                    ('WEIG').
> AIPS 1: APARM      *all 0                  (1) >0 => do 3-D corr.
> AIPS 1:                                       ONLY for snapshots
> AIPS 1:                                    (2) Parallactic angle (deg)
> AIPS 1:                                    (3) Zenith angle (deg)
> AIPS 1:                                    (4-8) radial scaling parms
> AIPS 1:                                    (9) Linear scaling
> AIPS 1: PBPARM     *all 0                  Beam parameters (NMAPS > 1)
> AIPS 1:                                    (1) Cutoff; (2) Use (3)-(7)
> AIPS 1:                                    (3)-(7) Beam shape
> AIPS 1: NOISE      *all 0                  Relative uncertainties by
> AIPS 1:                                    pointing: 0 -> image header
> AIPS 1: BADDISK    *all 0                  Disks to avoid for scratch
> 
> What could be the reason?What can be done to fix this?

I do not know - when I try FLATN I seem to get the same performance or 
better in 31DEC08 than I do in the other versions.  Are you sure some 
other parameters have not changed?  8192x8192 is very large (1/4 Gbyte 
of ram for a single copy of the image, 1/2 Gbyte since there is also a 
weight image) - you may be thrashing in the swap area.

> is there a way to install DEC07 version on my machine keeping the data 
> areas unaffected(to avoid loading all the data all over again in aips)?
> 
AIPS installations do not affect pre-existing data areas.  You may 
install 31DEC07, leaving 31DEC08 in place, and your data areas will not 
be affected.  Note that FLATN has not changed in 2008.

Eric Greisen