You can plot the values by index and show the respective values uisng text.
Example:
x = [5 10 100 1000] ;
y = rand(size(x)) ;
bar(y)
text(1:length(x),y,num2str(x'),'vert','bottom','horiz','center');
Or, use xticklabels and show the values at the x-axes.
Example:
x = [5 10 100 1000] ;
y = rand(size(x)) ;
bar(y)
xticklabels(x)
