FUNCTION     MAGERRSUM, ARG, WC=WC

;+
; NAME:
;	MAGERRSUM
;
; PURPOSE:
;	Sum magnitude errors (companion routine to MAGSUM)
;
; MODIFICATION HISTORY:
;	27 Jul 2007	Written by Mattia Vaccari
;-

if not(keyword_set(wc)) then wc=99.0

if n_elements(arg) eq 0 then begin

  print,'Argument is undefined! Returning -1...'
  res=-1.0
  goto,FIN

endif else if n_elements(arg) eq 1 then begin

  print,'Argument has only one element! Returning argument...'
  res=arg
  goto,FIN

endif

res=-1.0

;j=where(arg ne wc)
j=where(abs(arg-wc) gt 1.e-3)

;if (where(arg ne wc))[0] ne -1 then res=total(arg)/sqrt(n_elements(arg)) else print,'No Valid Arguments! Returning -1...'
if j[0] ne -1 then res=total(arg[j])/sqrt(n_elements(arg[j])) else print,'No Valid Arguments! Returning -1...'

FIN:

;if res eq wc then res=-1.0
if abs(res-wc) lt 1.e-3 then res=-1.0

return, res

end