%twoplots: create two plots with adjacent x-axes. 
top = subplot('position',[0.0929    0.5    0.8643    0.396]);
set(top,'xaxislocation','top','box','on')
bottom = subplot('position',[0.0929    0.104    0.8643    0.396]); 
set(bottom,'xaxislocation','bottom','box','on')