;+
; NAME: 
;    ISNUMERIC
; PURPOSE:
;    Test if the variable is a number
;
; CALLING SEQUENCE:
;    result = ISNUMERIC( X )
;
; INPUTS:
;    X = A variable to be tested as numerical value
;
; OUTPUTS:
;    RESULT= A boolean indicating if X is a number (1) or not (0)
;
; EXAMPLE:
;      IDL> print, isnumeric(5)
;             1
;      IDL> print, isnumeric('5')
;             1
;      IDL> print, isnumeric('A')
;             0
; MODIFICATION HISTORY:
;    Original Version written in June 2013, B. Carry (IMCCE)
;-
function isnumeric, input
  on_ioerror, false
  test = double(input)
  return, 1
  false: return, 0
end