;+
;
; @file_comments
; function called by [XYZ]TICKFORMAT (see the help to see how to use it) to
; label axes in longitude.
;
; @categories
; Graphics
;
; @param AXIS
; It is the axis number: 0 for X axis, 1 for Y axis, 2 for Z axis.
;
; @param INDEX
; It is the tick mark index which starts at 0.
;
; @param VALUE
; It is the default tick mark value (a floating-point number).
;
; @returns
; A string, used automatically to label
;
; @history
; Sebastien Masson (smasson\@lodyc.jussieu.fr)
;                       ???
;                       14/10/1999 format of labels
;
; @version
; $Id$
;
;-
FUNCTION lonaxe, axis, index, value
;------------------------------------------------------------
; We put back value in the segment [0,360[
;
  compile_opt idl2, strictarrsubs
;
   lon=value mod 360
   if lon lt 0 then lon=lon+360
; format of labels:
   case 1 of
      lon EQ round(lon):fmt = 'i4'
      10.*lon EQ round(10.*lon):fmt = 'f6.1'
      ELSE:fmt = 'f7.2'
   endcase
; we write the label
   if lon lt 180 then nom=string(lon,     format='('+fmt+',''E'')')
   if lon gt 180 then nom=string(360-lon, format='('+fmt+',''W'')')
   if lon eq 180 then nom=string(lon,     format='('+fmt+')')
;
   return, nom
end