AIPS NRAO AIPS HELP file for XBASL in 31DEC19



As of Tue Dec 18 4:10:53 2018


XBASL: Fits n'th order polynomials to rows of images

INPUTS

INNAME                             Input image name (name)
INCLASS                            Input image name (class)
INSEQ             0.0     9999.0   Input image name (seq. #)
INDISK            0.0        9.0   Input image disk unit #
OUTNAME                            Output image name (name)
OUTCLASS                           Output image name (class)
OUTSEQ           -1.0     9999.0   Output image name (seq. #)
OUTDISK           0.0        9.0   Output image disk unit #.
BLC                                Bottom left corner of input
TRC                                Top right corner of input
YINC              0.0      128.0   Do every YINCth row
ZINC              0.0      128.0   Do every ZINCth plane
FLUX              0.0              Flux cutoff (see HELP)
DOOUTPUT         -1.0        1.0   Write images of parms
DOCONT           -1.0        1.0   > => retain continuum
DOSLICE          -1.0        2.0   Plot data on TEK/TV
DOMODEL          -1.0        1.0   Plot model on TEK/TV
DORESID          -1.0        1.0   Plot residuals on TEK/TV
PIXRANGE                           Min,Max of image intensity
                                     Max <= Min => entire range
LTYPE          -410.0       410.0   Type of labeling: 1 border,
                                   2 no ticks, 3 standard, 4 rel
                                   to center, 5 rel to subim cen
                                   6 map pixels
PIXVAL           0.0               Display if peak < PIXVAL
ORDER            0.0          4.0  Max order of polynomial
NBOXES           1.0         40.0  Max number of baseline
                                   windows
BOX              0.0       4096.0  Begin/end channel numbers for
                                   windows 1 - NBOXES
DOTV            -1.0          1.0  > 0 use TV instead of TEK
GRCHAN           0.0          7.0  TV graphics channel to use
BADDISK                            Disk(s) to avoid for scratch

HELP SECTION

XBASL
Task:  Fits n'th order polynomials to each row of an image.  (Normally
       XBASL will be used on images with frequency or velocity as the
       first axis, but it will procede with others as well.)  The task
       fits up to 4'th order plus a constant baseline to each row and,
       optionally, writes up to 4 + 2*ORDER n-1 dimensional images
       containing the fit parameters and their uncertainties.  It will
       always write the image corrected for the baseline (i.e. with the
       baseline function, optionally minus its average, subtracted).
       With a careful choice of input parameters, the task is capable of
       running in a batch-like mode.  However, an interactive mode
       (using the TEK or TV graphics terminal) is recommended.  Note
       that, since the TEK and TV are not allowed in AIPS batch jobs,
       XBASL turns off all interactive options and TV/TEK displays when
       it is run in batch.
Adverbs:
  INNAME.....Input image name (name).       Standard defaults.
  INCLASS....Input image name (class).      Standard defaults.
  INSEQ......Input image name (seq. #).     0 => highest.
  INDISK.....Disk drive # of input image.   0 => any.
  OUTNAME....Output image name (name).      Standard defaults.
  OUTCLASS...Output image name (class).     Standard defaults.
             Used only for the corrected image.  The OUTCLASSes
             for the fit parameters are CONST and DERIVn and for the
             uncertainties are DCONST and DDERVn.  The "flux" (average)
             of the baseline function is written with OUTCLASSes of FLUX
             and DFLUX.
  OUTSEQ.....Output image name (seq. #).   0 => highest unique.
  OUTDISK....Disk drive # of output image. 0 => highest number with
             sufficient space.
  BLC........Bottom right corner in input image of desired subimage.
             Default is entire image.
  TRC........Top right corner in input image of desired subimage.
             Default is entire image.
  YINC.......Do only every YINC'th row (beginning at BLC(2)).
  ZINC.......Do only every ZINC'th plane (beginning at BLC(3)).
  FLUX.......A flux cutoff in the same units as the input image (i.e.
             Jy/beam).  If a row does not have three consecutive points
             above this level - or below minus this level, no baseline
             is fit to the row.  Note that the row values are tested
             after subtracting a linear baseline for this test.
             0 => 0.00005.
  DOOUTPUT...True (> 0) requests that the parameter and uncertainty
             images be catalogued (see OUTCLASS).
  DOCONT.....True (> 0) implies subtract the baseline and add the
             average of the baseline from the output.  This attempts to
             retain the continuum (if any).  False (<= 0) is used when
             the continuum is zero, or already removed.
  DOSLICE....True (> 0) implies plot the data on the TEK or TV.  > 1
             also requests a TEK/TV plot of the initial guess.  It
             must be set > 1. if you wish the option to correct
             initial guesses with the TEK cross hairs or TV cursor.
             If DOSLICE > 1 and NGAUSS > 1, the program pauses after
             plotting its initial guess and
             requests user input from the terminal.  Hit RETURN to
             procede with the program's initial guess.  Enter BAD to
             have the solution for the row blanked and E to have the
             program request your guidance as to an altered set of
             baseline windows.
  DOMODEL....True (> 0) requests a plot of the final model for each row
             on the TEK or TV.
  DORESID....True (> 0) requests a plot of the final residual values in
             each row.  If any one or more of DOSLICE, DOMODEL, or
             DORESID is true, then the program will pause after each row
             and request input from the terminal.  At that point, you
             may enter BAD to have the solution blanked or simply a
             RETURN to keep the answer.  One may also enter RETR to loop
             back and try again with a new set of baseline windows.
  PIXRANGE...Min,Max of Image intensity.  0,0 => min,max of EACH row
             (separately).  Note that this will mean some plots are at
             too fine a scale and that the residuals will appear only if
             the slice contains a sufficient range about 0.0.
  LTYPE.......Labelling type, see HELP LTYPE for details:
              1 = border, 2 = no ticks, 3 or 7 = standard, 4 or 8 =
              relative to ref. pixel, 5 or 9 = relative to subimage
              (BLC, TRC) center, 6 or 10 = pixels.  7-10 all labels
              other than tick numbers and axis type are omitted.
              Less than 0 is the same except that the plot file
              version number and create time are omitted.
              Add n * 100 to alter the metric scaling.
  PIXVAL.....Plot row only if the peak value < PIXVAL.  Limits the plots
             to those of uncertain intensities.
  ORDER......The maximum allowed order for the polynomial.  0 is a
             constant, 1 is linear, 4 is a bit much and is the maximum
             allowed.
  NBOXES.....The number of windows in each row (maximum) to be used in
             fitting the baseline up to 20.  This may be changed
             interactively, reducing it or raising it.  The adverb
             value is really used only to select how much of BOX is
             used initially and what is done in non-interactive
             modes.  If NBOXES=0, the outer 1/10th's of BLC to TRC are
             set as the initial pixels to examine for valid data.
  BOX........NBOXES pairs of channel numbers specifying the beginning
             and end channel numbers of each of the baseline windows.
             These numbers may be entered with the TEK/TV cursor in
             interactive modes.  If NBOXES>0 and BOX=0, the initial
             boxes are all pixels from BLC(1) to TRC(1).
  DOTV.......> 0 => use TV, otherwise the TEK emulator is used.  This
             emulator sometimes does not work well on Linux systems.
  GRCHAN.....TV graphics channel to use.  0 -> use more than one to
             allow color to contain extra meaning.
  BADDISK....Disk drives to avoid for scratch files.

EXPLAIN SECTION


In interactive modes, the task selects a row to be fit and plots it on
the display (REK or TV) screen.  The windows are plotted as boxes with
the left and right sides as vertical lines centered on the flux value
at the end pixels and the top and bottom lines connect these lines
together.  The slope of the plotted boxes is not related to the order
of the fit.

1.   It then asks you what order of fit to use, any order up to and
   including the value of ORDER is allowed.  The answer is in a fixed
   format: the first character must be c or C and the second character
   must be a number.

2.   It then asks you what to do with this row.  Answer:
   B or b  to skip this fit and copy the row to the output
   Q or q  to abort the task now
   E or e  to enter new fitting windows interactively
   else    to continue with current windows

3.   If entering new fitting windows, it asks you to position the
   cursor at the start of window 1 and the the stop of window 1, then
   the start of window 2, the stop of window 2, etc.  The loop exits
   when you select an X value outside the plot.  Note that you do not
   have to set the points working from left to right - if the point
   marked as the start of window n is at a higher X pixel then the
   point marked as the stop of window N, they will be reversed by the
   code.  The windows can also occur in any order.  If you are using
   the TV, the task will also leave the loop if you hit button D.
   Note, that the window is not entered in the list until the stop
   point is set.

4.   After doing a fit and plotting the requested parameters, it then
   asks you if you want
   R or r   to retry this row (you should enter a new set of windows)
   Q or q   to abort the task now
   B or b   to mark this solution as bad
   else     to subtract the solution, write the output and go on

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