/database                                                 July 2001

This subdirectory contains the IDL procedures, mostly written by Don Lindler,
(ACC/Goddard) to create and access an IDL database.   These database procedures
are currently used by the HST-ACS, HST-STIS, HST-WFC3 and SOHO  science teams. 
The LaTex file database.tex in the /text directory describes  the use of the
database procedures with an emphasis on astronomical  applications.     Further
information on the database software is available  in Chapter 3 and Appendix J
of "A User's Guide to the GHRS Software" available as a postscript file or as
.html help from  http://hrssun.gsfc.nasa.gov/daf/sw_docs.html

The database procedures require the non-standard system variables
!PRIV, !TEXTOUT, and !TEXTUNIT.   These can be added to the IDL session 
by using the procedure ASTROLIB.

Sample astronomical catalogs, formatted as IDL databases, are available in the
/zdbase directory.   These include the Yale Bright Star Catalog, the 
RC3 Galaxy catalog, and a catalog of HST observations.

Very large (> 15 million entries) databases may require the use of 64 bit
integers - and at least V5.2 -- internally.     Updated versions of DBINDEX,
DBINDEX_DBF, DBFIND_SORT, and DBEXT_IND are available in
ftp://idlastro.gsfc.nasa.gov/pub/v53.

23-Jul-2001: DBCREATE, DBFIND, DBFIND_SORT, DBXVAL, DBINDEX_BLK, DBBUILD -
             Now allow user to specify items with 64 bit or unsigned integer
             datatypes.

2-Dec-2000:  DBINDEX, DBEXT_IND - Now allow multiple-valued index items
             Minor updates to database.tex file

17-Nov-2000: DBFIND, DBFIND_ENTRY, DBFIND_SORT, DBSEARCH, IMDBASE - Now
                have a Count keyword; deprecate use of !ERR

11-Oct-2000: DBXVAL - Work for multiple-valued strings

08-Aug-2000: DBPRINT - Change a loop index to type LONG (sigh...)

5-Feb-2000:  DBPRINT - Only byteswap when necessary, for much improved speed.

1-Nov-1999:  DBINDEX, DBEXT_DBF - Now allow a maximum of 18 instead of 15 items

21-Sep-1999: DBPRINT - Fixed occasional problem when /NOHEADER supplied

04-Sep-1999: DBCIRCLE - Fixed bug that could cause some entries to be missed

05-Aug-1999: DBMATCH - Removed loop (faster) for substring searches
             DBMATCH() - Change some loop indicies to type LONG
             DBCIRCLE() - Leave output DIS vector unchanged if no entries found