samer@20: function X=shift_beat(delta,X)		
samer@56: 	beatpos=X(:,4);
samer@56: 	if any(diff(beatpos)<0)
samer@56: 		disp('WARNING: metrical position not monotonic');
samer@56: 	end
samer@56: 	X(:,4)=beatpos+delta;
samer@20: end
samer@20: