Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.atnf.csiro.au/computing/software/gipsy/tsk/flat.dc1 Дата изменения: Mon Mar 20 08:41:57 2000 Дата индексирования: Thu Jan 15 23:26:18 2009 Кодировка: Поисковые слова: hst

Program: FLAT

Purpose: Apply a flat field correction to a map by fitting a
2-D polynomial to the background.

Category: MODELS, CALCULATION, FITTING, CALCULATION

File: flat.c

Author: M. Vogelaar

Keywords:

INSET= Give set, subsets:
Maximum number of subsets is 2048.
Dimension of the subsets must be 2.

BOX= Area which needs to be flat fielded [whole map]

OUTSET= Output Set/Subset(s)

ORDER= Order of polynomial to be fitted to the map [1]
highest allowed order is 21


** RANGE= Give range of levels to include in fit: [all levels]
Input consists of two values. The first value may
be greater than the second. See the description
for the correct use of this keyword.



Description: This program can be used for example to extract a
background by fitting a polynomial to it.
The program uses a set (INSET=) which usually
is blotted first. The subsets must be two dimensional.
The area on which FLAT works is given in BOX=
It writes the results to OUTSET= in the same box.
Beware if OUTSET= already exists. It only overwrites
data in the given box. A polynomial plane will be fitted
to the data using the least squares method. The order
of this polynomial is given in ORDER= This number cannot
exceed 21.
Values outside the range defined in RANGE= are treated
as blanks, i.e. they are not included in the fit and are
interpolated after a plane is fitted to the data.
Examples for the use of the RANGE= keyword:

RANGE=2, 5
(IF 2blank)

RANGE=5, 2
(IF 2blank ELSE include in fit)

At the RANGE= keyword, the values -INF and INF can
be input also. These values represent the minimum
and maximum values of the current system.

RANGE=5, INF
(IF value>5 THEN include ELSE value==>blank)

The fitted background can be subtracted from the
original set with the program COMBIN.


Example:

Notes:

Updates: Oct 14, 1991: MV, Document created.