;+
;
; @file_comments
; erase a variable
;
; same thing like <proidl>DELVAR</proidl> 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
;
; @examples
;   IDL> a=1
;   IDL> undefine,a
; % Compiled module: UNDEFINE.
;   IDL> help, a
; A               UNDEFINED = <Undefined>
;
; @history
; trouve sur la page web de D.Fanning
; <a href="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 <proidl>DELVAR</proidl> to
;delete an IDL variable and make it undefined. Inside of procedures
;and functions, I use this little program named <pro>undefine</pro> that I got
;from Andrew Cool at the DSTO High Frequency Radar Division in
;Adelaide, Australia.
;
; @version
; $Id$
;
;-
PRO undefine, varname
;
  compile_opt idl2, strictarrsubs
;
  IF n_elements(varname) NE 0 THEN tempvar = SIZE(TEMPORARY(varname))
END