Function: date_ax

CALL:

date_ax(xa, ya, postprocess)

DESCRIPTION:

Supply a number of axes with date ticks

INPUT: 

   xa: x axes handles
   ya: y axes handles
   postproces: optional boolean, default true.
               If true update add day, month and year to first tick and
               to ticks where day month and year change.
locale any 
string with language, e.g. it, es, nl, en, de, fr or zh

OUTPUT: 

   none

EXAMPLE: 

      plot ....
      %install zoom with date_ax
      hax=gca;
      opt.move=@(o,e)date_ax(hax);
      zoomtool(1,opt);
      date_ax(hax);

APPROACH: 

  It is assumed that data are specified in datenum format