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1.2 Using IDL Routines

 IDL procedures are basically programs which execute a series of IDL commands and/or other procedures. Most of the operations you will perform on your IUE data will be done by executing IDL procedures. Intrinsic IDL procedures and non-experimental IUEDAC software are compiled and executed by typing the procedure call statement followed by a < CR >. If you do not remember the calling sequence of an IUEDAC procedure, just typing the procedure name followed by a < CR >.

Software in your own directory may be compiled by typing the procedure name. To execute the procedure, type the calling sequence. Your current directory is the first place that IDL will look for procedures, so if you have customized versions of procedures there, they will be accessed before those in the IUEDAC or IDL libraries.

Once a procedure has been compiled, you should not need to recompile it for the duration of your current IDL session. It must be recompiled if you have terminated the IDL session and started another session (e.g., by typing ``iuerdaf''). If you modify a procedures during your IDL session, it must be recompiled, or IDL will continue to use the saved (previously compiled) version. IDL automatically compiles all the subprocedures needed to run. For instance, running IUESPEC will automatically compile IUEPLOT and LABEL.

IMPORTANT: If you interrupt a procedure once it has begun to execute, or have an error during the execution of the procedure, you will need to type RETALL before attempting to reexecute it. You may also find some files are left open and need to be closed. Type HELP,/FILES to see what logical units are still in use and then type FREE_LUN,n where n is the listed logical unit number.

The calling sequences of the procedures described herein have been shown (when possible) with the convention that required parameters are written in uppercase letters, and optional parameters are specified with lowercase letters (IDL is not case sensitive). For example:

IUE_IDL>RV,h,W,F,e    can be executed as

rv,w,f   or   rv,h,w,f,e

(Parameters which are strings, such as file names, are always enclosed with single quotes.) Some procedures have optional ``keyword'' parameters. The keyword is set equal to a value in the calling sequence. For instance,

LBL,'IMAGET',LINE1,NLINES,clip=fnvalue (calling sequence)

lbl,'swp12345slg',40,12,clip=5000 (example)

has one such keyword parameter - ``clip''. You replace the word ``fnvalue'' by the appropriate flux number value, and type the calling sequence as shown. These keywords will be written as ``keyword=value''. Certain ``logical'' keyword parameters are set equal to either zero or one, with zero being the default. There is a shorthand notation for setting these equal to one. For example,


In the example above, you would actually include ``/log'' in the calling sequence if you wished to use that option (in this case, the ``/log'' keyword creates a file containing the results of the program). Such keywords will be written with a slash (``/keyword'').

Table 1.4: Compiling Procedures
Expression Definition
.run explib:procedure Compiles ``'' in the experimental library. Note: ``explib'' is a logical; not all operating systems support logicals.
explib,1 Adds the experimental library to your search path.
explib,-1 Removes the experimental library from your search path.
explib,0 Tells you if the experimental library is included in your search path.
procedure,param1,param2,...,paramn Executes the procedure.
yourpro,param1,param2,...,paramn Executes your software. Also compiles YOURPRO if it is in your current directory and has not been already compiled during the current session.
.run [.subdir]anotherpro Compiles a procedure in another directory. In this example the VMS path specification was used.
procedure Displays calling sequence of procedure. This is standard for IUEDAC software.

next up previous contents
Next: 1.3 Experimental Software Up: 1 INTRODUCTION Previous: 1.1.2 NEWSIPS File Names