AIPS HELP file for XGAUS in 31DEC09
As of Sat Nov 21 20:24:30 2009
XGAUS: Fits 1-dimensional Gaussians to 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)
BCHAN -1.0 512.0 # channels at left for
baseline (-1 => no baseline)
ECHAN -1.0 512.0 # channels at right for
baseline (0 => none)
DOOUTPUT -1.0 1.0 Write residual image
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 0.0 6.0 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
NITER 0.0 4000.0 Max # fit iterations
0 -> 100.
NGAUSS 1.0 4.0 Number of Gaussians
Guess of model parameters
GMAX 0.0 Peak of component (JY)
GPOS X position (pixels wrt the
reference pixel)
GWIDTH 0.0 FWHM of comp. (pixels)
Solve for model parameters?
DOMAX -1.0 1.0 Solve for GMAX?
DOPOS -1.0 1.0 Solve for GPOS?
DOWIDTH -1.0 1.0 Solve for GWIDTH?
DOTV -1.0 1.0 > 0 use TV instead of TEK
GRCHAN 0.0 7.0 TV graphics channel to use
BADDISK Disk to avoid for scratch
HELP SECTION
XGAUS
Task: Fits one-dimensional Gaussians to each row of an image.
(Normally XGAUS 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 Gaussians plus a linear baseline
to each row and writes up to 4 + 8*NGAUSS n-1 dimensional
images containing the fit parameters and their uncertainties.
Optionally, it will write the residual image as well. With a
careful choice of input parameters, the task is capable of
running in a batch-like mode. However, particularly for NGAUSS
> 1, an interactive mode (using the TEK graphics terminal or
the TV graphics planes) is recommended. Note that, since the
TV and TEK are not allowed in BATCH jobs, XGAUS turns off all
interactive options and TEK/TV displays when it is run in
batch.
We strongly recommend beginning with DOTV=1 (the Tek crosshairs
have trouble), GRCHAN=0 (use color to differentiate what is
plotted), DOSLICE=2 (allow initial guesses to be set),
DOMODEL=1 (see what was fit). The initial guess uses channels
1-BCHAN and Nchan to Nchan-ECHAN+1 to set the DC level and
slope. It is plotted as X signs. The data are plotted with
stepped connecting lines, the fit as a smooth connecting line,
and the residual as a dashed line. With GRCHAN=0, the guess is
in graphics channel 2 (usually green), the data in 1 (usually
yellow), the fit in 4 (usually cyan), and the residual in 3
(usually pink).
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 residual image. The OUTCLASSes
for the fit parameters are SLOPE, CONST, AMPLn,
CENTRn, and WIDTHn and for the uncertainties are
DSLOPE, DCONST, DAMPLn, DCENTn, and DWIDTn.
The "flux" of each component (ampl * width * 1.06)
is written with OUTCLASSes of FLUXn and DFLUXn.
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, no component
is fit to the row. It is also used to limit the
points which determine the initial guess.
BCHAN......Number of points at the left edge of the input row
used to determine the initial guess for the linear
baseline. -1 => do not fit a baseline.
0 => no channels at the left, i.e. the initial
guess for the baseline slope will be zero.
ECHAN......Number of points at the right edge of the input row
used to determine the initial guess for baseline.
0 => no channels at the right, i.e. the initial
guess for the baseline slope will be zero.
DOOUTPUT...True (> 0) requests that the residual (data-model)
map be catalogued (using OUTCLASS).
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 a better initial guess. During the
entering of a new initial guess with the TEK crosshairs
or TV cursor, you may request that a particular component
be null (held at 0 amplitude) by indicating that its peak
or halfwidth point is outside the plot area.
DOMODEL....True (> 0) requests a plot of the final model for each
row on the TEK/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. The program will warn you
if any of the fit parameters are way out of normal
limits. For NGAUSS > 1, one may also enter RETR to loop
back and try again with a manually entered initial guess.
PIXRANGE...Min,Max of Image intensity. 0,0 => min,max of EACH
row (separately).
LTYPE......Labelling type: 1 = border, 2 = no ticks, 3 = standard,
4 = relative to center of row, 5 = relative to subimage
(BLC, TRC) center 6 = pixels in original map
PIXVAL.....Plot row only if the peak value < PIXVAL. Limits the
plots to those of uncertain intensities.
NITER......Maximum function evaluations during the fit of each row.
(< 10 -> 100 for NGAUSS > 1, < 100 -> 150 for 1
Gaussian)
NGAUSS.....Number of Gaussians to fit (between 1 and 4).
GMAX.......Estimate of brightness of components 1 through 4.
0 => use data at GPOS. Ignored if NGAUSS = 1.
GPOS.......Estimate of central pixel of comps 1 through 4 in
pixels from the reference pixel (increases to the
right). Ignored if NGAUSS = 1.
GWIDTH.....Estimate of the FWHM in pixels of comps 1 - 4.
Ignored if NGAUSS = 1. If NGAUSS > 1, the program will
use either the user initial guess or the previous
solution as the new initial guess - whichever has a lower
rms. To indicate that the program should always use the
previous solution, set all GWIDTH to 0. Of course, you
may always enter a revised initial guess with the TEK/TV.
DOMAX......<= 0. means hold this parm fixed (NGAUSS > 1 only).
DOPOS......<= 0. means hold this parm fixed (NGAUSS > 1 only).
DOWIDTH....<= 0. means hold this parm fixed (NGAUSS > 1 only).
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