function r=checktilt(rot,angle)
%
%  angle = [ rol1 ; pit1 ; rol2 ; pit2]
% rotate pit2,rol2 by rot and then compare results

[rol21,pit21]=uvrot(angle(3,:),angle(4,:),rot);

dr=rol21-angle(1,:);
dp=pit21-angle(2,:);

r=(dr-mean(dr)).^2 + (dp-mean(dp)).^2;
r=sum(r);