Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.atnf.csiro.au/computing/software/gipsy/tsk/fixhed.dc1 Дата изменения: Mon May 29 18:55:23 1995 Дата индексирования: Fri Jan 16 01:12:10 2009 Кодировка: Поисковые слова: mercury program

Program: FIXHED

Purpose: Add, change, delete or list item(s) in set header

Category: HEADER, UTILITY

File: fixhed.c

Author: M. Vogelaar

Keywords:

INSET= Give set (, subsets) to work on:

Maximum number of subsets is 2048.
Usually descriptors are added or changed at top level,
but if you work on subset level, it will be possible
to work on all given subsets at the same time.


ITEM= Give name of header item: [show header]
or (after the first prompt):
Give name of header item: [end program]

This keyword is asked in a loop. You end the
program if you press carriage return.
Input is a name associated with a keyword in the header.
After the first input, the prompt will also show
the mode that you are currently working in (see MODE=).
The length of the string that you enter may not exceed
8 characters.


There are two special entries for ITEM=

ITEM=LIST If you enter ITEM=LIST, a list with recommended GIPSY
keywords with explanation is displayed.
ITEM=HEAD If you specify ITEM=HEAD, the sorted contents of the
header at top- or subset level is displayed.


** MODE= Operation mode: A(dd),D(elete),C(hange): [A]

You need to specify only one character.
FIXHED can Add, Change and Delete header items.
If ITEM= is found in the header of INSET= then the
default is A(dd).
If ITEM= is NOT found in the header of INSET= then the
the default is C(hange).
If there is some kind of conflict (for example changing
an item that isn't present in the header) then the
keyword is asked UN-hidden.
The mode of operation can be changed within the ITEM=
loop (e.g. ITEM=maxbase MODE=d).


** TYPE= Give type of item I/R/D/L/C/T/H: [back to item loop]

The type of keyword can be one of:
I -Integer numbers
R -Real numbers
D -Double precision numbers
L -Logical variables as T or F in header,
but input can be YES, JA and TRUE, NO, NEE and
FALSE, or any abbreviations.
C -Character variable. A string that can contain
spaces. Quotes are added by the program. The
string cannot exceed 18 characters
H -Commentary FITS keywords COMMENT or HISTORY.
Keyword and contents cannot exceed 80 characters.
T -Text entry NOT FITS. Only used in special cases!
(See description)

The keyword TYPE= is hidden if the specified
item (and its type) is found in a list (ITEM=LIST) with
general keys or in the header of the specified input
set.



It is possible to apply adding or deleting (not
changing) to all subsets.


1) Add on subset level(s):
** ALL= Apply to all remaining levels? Y/[N]

ALL=Y can be typed any time to start copying the
last entered value of an item to all remaining
subset levels.


2) Delete on top level (no subset(s)):
ALL= Delete item on ALL levels? Y/[N]


3) Delete on subset level:
** ALL= Delete on all remaining levels? Y/[N]

ALL=Y can be typed any time to start deleting the
last entered value of an item to all remaining
subset levels.
For ALL=N you will be prompted at each level with
OK= before an item is removed on the current subset
level.


OK= Subset nr ...: Ok to delete item? Y/N/[stop]
Note that 'stop' only stops the current action
and returns to the ITEM= loop.


VALUE= MODE=Add:
Add (type) for (descriptor)= [stop]
(on subset level)
Subset nr ...: Add (type) for (descriptor)= [stop]

MODE=Change:
New value for %.*s= [do not change]
(on subset level)
Subset nr ...: New value for %.*s= [do not change]


COMMENT= MODE=Add:
Add a comment [none]

MODE=Change:
Give new comment [do not change]


If the operation mode is A(dd), it is possible to
create a FITS style comment here. If the mode is
C(hange), first the old comment is displayed and
the user is prompted to give a new one. There are
no comments for the T(ext) and H(istory) type.


LINE= Give number of line to change: [stop]

If items HISTORY or COMMENT are specified, the old
contents at top- or subset level is displayed with a
line number. You can change one line at a time. If you
press carriage return the changed lines are written to
the descriptor file and the program returns to the
ITEM= prompt.


Description: GIPSY data consists of an image file with floating point
numbers and an associated file called 'descriptor' or
'header' file. This file describes structure and coordi-
nate system of the image data by means of FITS (Flexible
Image Transport System) keywords. Each item is stored in
the header in a special format with the basic grammar:

keyword = value / comment

In GIPSY descriptor files we distinguish the formats:
Integer, Real, Double, Logical, Character and the so
called commentary formats (HISTORY and COMMENT).

There is also one non FITS format implemented in FIXHED
called Text. This format will be used only in special
cases (See APSET keyword in the examples)..


Examples:

The number of interferometers used in an observa-
tion is stored as an integer, its associated header
keyword is 'NINTF'.
The maximum of a map is stored as a real in 'DATAMAX'.
The total bandwidth of an observation is stored as a
double in 'BANDW'.
The date of the observation is stored as a character
string and its associated keyword is 'DATE-OBS'.

The set, subset used for an antenna pattern is stored in
text form (one or more character strings). Input looks
like: APSET=ANTPAT FREQ 1.
This string can be a long string so it can not be stored
in character format. It will be stored in Text format.
However, the item will not be recognized as a real
FITS item and therefore cannot be transported.

Two keywords, COMMENT and HISTORY are of type History,
but have a text format also. New information is appended
to existing data in lines with a maximum of 80 characters.
With the program FIXHED you can add, change, delete or
list these items on top level (specify only the name of
a set at the INSET= prompt) or at subset level (specify
name and subsets). For each item of type Integer, Real,
Double, Logical or Character, a corresponding FITS
comment can be added or changed.

The keywords describing the structure of the set must be
given with an integer number appended to it like CTYPE3.
FIXHED checks name, number and level for these keywords.
Only keywords with NAXIS cannot be changed.

If ITEM=HEAD all descriptors on current level will be
displayed in alphabetical order. If tables are encountered
name and type are listed before the list of keywords only
if the output mode is set to TEST.


Example: Change position angle item (BMPA) in set AURORA on top level,
after displaying the contents of its header.

Updates: Jul 14, 1990: VOG, Document created.
May 18, 1992: VOG, Table detection.
May 29, 1994: VOG, Display GDS errors.
Update of documentation.


Example:

FIXHED,INSET=TESTSET
Set TESTSET has 3 axes
RA-NCP from -9 to 10
DEC-NCP from -9 to 10
FREQ-OHEL from 0 to 9
FIXHED working at top level
Use ITEM=HEAD to get a list of ALL descriptors on current level.
Use ITEM=LIST to get a list of recommended GIPSY keywords
FIXHED,ITEM=

HEADER at top level
===============================
APSET = GAUSS FREQ 0
BANDW = 0.31250000000000D+00 / total bandwidth of observation
BMMAJ = 0.35966360473633D+03 / major axis (FWHM) of beam (arcsec)
BMMIN = 0.35966360473633D+03 / minor axis (FWHM) of beam (arcsec)
BMPA = 0.00000000000000D+00 / pos. angle of major axis of beam (N->E)
BUNIT = 'WU ' / data units (WU,MJY/SR,...)
CDELT1 = 0.10000000000000D-01
CDELT2 = 0.10000000000000D-01
CDELT3 = 0.10000000000000D+09
CROTA1 = 0.00000000000000D+00
CROTA2 = 0.00000000000000D+00
CROTA3 = 0.00000000000000D+00
CRPIX1 = 0.10000000000000D+02
....etc...

HISTORY/COMMENT
===============
HISTORY : DUMMY SET FOR TESTING 29/11/90
COMMENT : NOT A REAL SET!

FIXHED,ITEM=BMPA

============================= FIXHED ========================
FIXHED tries to CHANGE item [BMPA] at set level.
Item BMPA (pos. angle of major axis of beam (N->E)) is known
and stored as a double.
Item found in HEADER at SET level.
=============================================================
Old value BMPA= 0.000000
FIXHED,VALUE=45
FIXHED,COMMENT=Vavlue changed from 0 to 45
FIXHED,ITEM=
FIXHED - +++ FINISHED +++