Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.atnf.csiro.au/computing/software/gipsy/tsk/trace.dc1 Дата изменения: Mon Jul 22 19:09:08 1996 Дата индексирования: Fri Jan 16 00:08:31 2009 Кодировка: Поисковые слова: ngc 6781

Program: TRACE

Purpose: TRACE plots image values at user given positions
as function of distance to a plot centre (in 2-d
(sub)sets).

Category: ANALYSIS, PLOTTING

File: trace.c

Author: M.G.R. Vogelaar

Keywords:

INSET= Give set (, subset):
Only one subset is allowed. The dimension of the subset
must be 2.

XYBOX= Give size of box around one pixel: [3,3]
The resulting value at a selected position is an
average of the pixels in the defined box around that
position.

MODE= Manual mode or File mode? [M]/F
Input pixel positions manual or by file.

ASCINPUT= Give name of input Ascii input:
If MODE=F, ask for input file name. The file format is:
x1 y1
x2 y2
...
Maximum number of position pairs is 10000.
Numbers are separated by a space.

** GRIDS= Give grid spacings x, y: [header]
If nothing was found in the header of the set, this
keyword is asked unhidden with default [1,1].

STEPSIZE= Give step size for interpolation: [no interpolation]

CENTPOS= Give central pos.(x1, x2):
This position is used to determine the distance of user
selected positions with respect to the center. Physical
values are allowed.

INCL= Inclination of trace in degrees: [0.0]
If i is the inclination in degrees then
minor / major = cos(i).
For the number of inclinations see remarks at WIDTH=

PA= Position angle of major axis: [0.0]
Measured as per astronomical convention from north
to east.

POSITION= Give position x, y:
Physical values are allowed.

CONTINUE= C(ontinue), D(evice), P(lot), W(rite), Q(uit): [C]
C: Continue, get next position.
D: Continue but initialize plots again first.
P: Plot results.
W: Write results to file.
Q: Quit program.

DISTANCE= Distance in (T)race or wrt. (C)entre: [C]
If you want to plot or write the results, select what
kind of distance you want to use. Default is the
distance measured with respect to the centre. The other
option, DISTANCE=T, gives the distance in the trace you
followed in physical coordinates.


Before plotting, it is possible to adjust the size of
the plot with the hidden keywords:

** XMINMAX= Give Xmin, Xmax in plot: [calculated]

** YMINMAX= Give Ymin, Ymax in plot: [calculated]



Keywords to initialize plots:

** SUBDIV= View surface subdivisions x,y: [1,1]
It is possible to have more plots on the view surface.
The number of plots can vary in both directions x and y.

GRDEVICE= Give graphics device to [list of available devices]
plot on:

** PAPER= Give width (cm), aspect ratio: [0.0, 1.0]
Change the size of the (output) view surface.
The aspect ratio is defined as height/width.
The default is a calculated size and aspect ratio 1.

** LINEWIDTH= Give line width (1-21): [2]
Only required if a hardcopy device is selected.



Description: TRACE can be used to trace a curve in a 2-dimensional
subset. The plot will show amplitude versus distance
in physical coordinates. The distance can be measured
with respect to a user given center (DISTANCE=C) or
as a distance in the trace you follow (DISTANCE=T).
The positions in your trace are asked in a loop with
POSITION=. You can give this position in pixels or in
physical coordinates. A distance is calculated as the
distance in pixels times the grid spacings and
therefore plotted in physical coordinates. The distance
in a trace is calculated as the sum of the previous
distance in a trace and the distance to the previous
position. The positions can be read from the file
specified in ASCINPUT=, but you have to chose MODE=F
first then. If you want to see some results, select
CONTINUE=P for a plot. Plot software is initialized
with the keywords SUBDIV=, GRDEVICE=, PAPER= and
LINEWIDTH=. The size of the plot box is calculated
but can be changed by the hidden keywords XMINMAX=
and YMINMAX=. Before plotting the keyword DISTANCE=
must be specified with 'T' ( distance in trace) or 'C'
(distance with respect to the center given in CENTVAL=).
If you want the distance expressed in pixels, use the
hidden keyword GRIDS=1,1
The program interpolates between two positions in
steps defined by STEPSIZE=. The default is no inter-
polation. The grid spacings are displayed in the log
file and can be used as an indication how to chose
the stepsize.
It is possible to redirect the output to a file
specified by ASCOUTPUT=. This file will contain two
columns, the first one is the distance, the second one
is the amplitude. The results are in Ascii. The maximum
size of the input and output files are 10000 pairs of
numbers. An extra file with the same name and the
extension '.position' contains all (interpolated)
positions.


Updates: Aug 21, 1991: VOG, Document created.
Oct 10, 1991: WZ, PGPLOT standard names implemented
Jul 22, 1996: VOG, Changed CONTINUE= for use in COLA files