;------------------------------------------------------------
;------------------------------------------------------------
;------------------------------------------------------------
;+
;
; @file_comments 
; erase a variable
; same thing that delvar but usable in a program and usable 
; for one variable simultaneously
;
; @categories utilities  
; 
; @param varname {in}{required} The name of the variable we want erase
;
; @example IDL> a=1
;          IDL> undefine,a
;          % Compiled module: UNDEFINE.
;          IDL> help, a
;          A               UNDEFINED = <Undefined>
;
; @history trouve sur la page web de D.Fanning 
; http://www.dfanning.com :
;QUESTION: How do I make an IDL variable have a type "undefined"? 
;ANSWER: At the main IDL level you can use the IDL procedure DELVAR to
;delete an IDL variable and make it undefined. Inside of procedures
;and functions, I use this little program named UNDEFINE that I got
;from Andrew Cool at the DSTO High Frequency Radar Division in
;Adelaide, Australia.
;
;-
;------------------------------------------------------------
;------------------------------------------------------------
;------------------------------------------------------------
   PRO UNDEFINE, varname  
;
  compile_opt idl2, strictarrsubs
;
   tempvar = SIZE(TEMPORARY(varname))
   END