----- file created by makedoc on: Tue Mar  3 17:24:54 2009
----- Documentation for /scisoft/xop2.3/extensions/shadowvui/src/lib/loopsh.pro -----

 NAME:
	LOOPSH 
 PURPOSE:
	Runs shadow (source+trace) a number of times with the currently
	available system. It changes the source seed in the process 
	and allows the user to keep files for analysis.
 CATEGORY:
	SHADOW's utilities.
 CALLING SEQUENCE:
	loopsh, N, keyword_parameters
 INPUTS:
	N   Number of times that shadow has to be run.
 KEYWORD PARAMETERS:
	KEEP Array of strings with the files names to be kept.
		LOOPSH renames the files to the same name with the 
		"-i" extension, being i the run indes (from 1 to N).
		Use the keyword NFILES (in READSH, PLOTXY...) to load the
		resulting files.
	APPEND This keyword permits to avoid keeping disk files
		and allows the user to accumulate the result of the
		loop calculations in a structute containing a number
		of shadow/idl structures as n_elements(KEEP).
		Usage: Define a named variable with 1 or with 
		the structure where to append the result of the 
		calculation. Call LOOPSH with the keywords
		KEEP and APPEND switched on.
		See examples for more details
	NOLOST This keyword only works with the APPEND keyword.
		The effect is the same as the NOLOST keyword in
		the READSH function.
	ONLY_SOURCE When set then runs only shadow source (default=
		source+trace)
	ONLY_TRACE When set then runs only shadow trace (default=
		source+trace)
 SIDE EFFECTS:
 	Acces the UNIX shell. Create files.
 RESTRICTIONS:
	When using the APPEND keyword, the maximum number of
	elements allowed for KEEP is 10.
 PROCEDURE:
	Acces to the UNIX shell using spawn.
 	Runs SHADOW's seed, gen_source and trace (N times).
	Rename file names.
 EXAMPLES
	1) Make a shadow loop and save the files
	   start.03 and screen.0103 of each iteration
	   in start.03-i and screen.0103-i where 
	   the index i goes from 0 to NLOOPS
	loopsh,5,keep=['star.03','screen.0103']
	plotxy,'star.03',1,3,NFILES=5 ; example of analysis

	2) Like 1) but instead saving files it does save the 
	   result in an idl structure
	app = 1 ; initialize variable where to keep data
	loopsh,5,keep=['star.03','screen.0103'],append=app
	   The resulting structure app contains 2 tags: the 
	   first one corresponds to the files 'star.03', and
	   the second one to 'screen.0103'.
	plotxy,app.(0),1,3 ; example of analysis eqivalent
		to the previous example.
	   A help on the result may be:
	 for i=0,n_tags(app)-1 do help,/str,app.(i)

	3) After running 2), if we think the statistics is
	   not good, we can add to the structure app the result 
	   of other 2 shadow loops:
	loopsh,2,keep=['star.03','screen.0103'],append=app

 MODOFICATION HISTORY:
	M. Sanchez del Rio. ESRF. Grenoble, 24 May 1996.
	96/06/24 MSR (srio@esrf.fr) adds APPEND, NOLOST and 
		ONLY_(SOURCE,TRACE) keywords.


