function drw = year_axis( nrtick, Itick1, Itick2, yrlab, yrst );
 
%  YEAR_AXIS    Function used to :
%               - change the nr of x-tick-marks, and label
%                 them with the months of the year.
%               - add year labels underneath the x-labels.
%               - add minor ticks on the y-axis.
%
%  SYNTAX       year_axis( nrtick,Itick1,Itick2,yrlab,yrst );
%
%  Where :
%               - nrtick = nr of tick marks .
%               - Itick1  = position of the I ticks on the upper xaxis.
%               - Itick2  = position of the I ticks on the lower xaxis.
%               - yrlab  = position of the 'year' labels.
%               - yrst   = year to start with.
 
set(0,'hideundocumented','no');
h = gca;
set(h, 'yminorticks','on');
% set(h,'xtick',[])
set(h,'xtick',1:nrtick);
set(h,'fontname','courier')
set(h,'fontsize',8)
set(h,'tickdir','out')
% set(h,'xticklabels',[]) ;
set(h,'xticklabels',['J';'F';'M';'A';'M';'J';'J';'A';'S';'O';'N';'D']) ;
set(h,'box','on')
set(h,'ticklength',[0.006 1.000])
ltk = 1:12:nrtick;
%ltk = 1:12:nrtick+1;
yr = yrst-1; xpos=0;
for( i = 1:12:nrtick-1 )
  yr = yr+1;
  xpos = xpos+1;
  text( ltk(xpos)-0.5 , Itick1,'I');
  text( ltk(xpos)-0.5 , Itick2,'I');
  if( i < nrtick-7 )
    text( ltk(xpos)+4.0 , yrlab, num2str(yr) );
  end
end




