function newlog = compute_errors(log, res, perc, max_theta)

	m3 = -res.est_r_l / res.est_d;
	m4 =  res.est_r_r / res.est_d;
	 
	n = size(log.T,2);
	for k=1:n
		T_k = log.T(k);
		w0 = ( m3 * log.phi_l(k) + m4 * log.phi_r(k) );
		o_theta(k) = T_k * w0;

		c3 = 0.5 * T_k * (-m3 * log.phi_l(k) + m4 * log.phi_r(k));
		if abs(w0*T_k) > 1e-7
			c4 = c3 * (   sin(w0*T_k)   / (w0*T_k) );
			c5 = c3 * ( (1-cos(w0*T_k)) / (w0*T_k) );	
		else
			c4 = c3 * 1;
			c5 = c3 * 0;
		end
		o_x(k) = c4 * res.est_d;
		o_y(k) = c5 * res.est_d;
		
		o_k = [o_x(k);o_y(k);o_theta(k)];
		sm_k = log.sm(:,k);
		e_k = oplus(res.est_laser, sm_k) - oplus( o_k, res.est_laser);
		errors(:,k) = e_k;
	end
	
	worst_indexes = [];
	threshold = perc;
	for j=1:2
	
		if j==1
			err = abs(errors(3,:));
		else
			err = sqrt(errors(1,:).^2 + errors(2,:).^2);
		end
		
		cut = floor(threshold*size(err,2));
		err_sorted = sort(err);
		th = err_sorted(cut);
		worst = find(err > th);
		fprintf('%d: cutting %d / %d\n', j, size(worst,2), size(err,2));
		worst_indexes = [worst_indexes worst];
	end

	worst = find(rad2deg(abs(o_theta)) < max_theta);
	worst_indexes = [worst_indexes worst];
	worst = find(rad2deg(abs(log.sm(3,:))) < max_theta);
	worst_indexes = [worst_indexes worst];
	
	worst_indexes = unique(worst_indexes);
	fprintf('Unique: %d \n', size(worst_indexes,2));
	good_indexes = setdiff(1:n, worst_indexes);
	
	newlog = select_indexes(log, good_indexes);
	newlog.good_indexes = good_indexes;
	newlog.worst_indexes = worst_indexes;
	newlog.old_residuals = errors;
	newlog.o_theta = o_theta; 

% plot errors	
if false

	figure
	subplot(3,1,1);
	plot(rad2deg(o_theta), rad2deg(log.sm(3,:)), 'r.');
	axis('equal');
	title('odometry \theta vs laser \theta');
%polyfit(rad2deg(o_theta), rad2deg(log.sm(3,:)), 1)
	xlabel('odometry \theta (deg)');
	ylabel('laser \theta (deg)');
	
	subplot(3,1,2);
	plot(rad2deg(o_theta), rad2deg(errors(3,:)), '.k');
	axis('equal');
	title('odometry \theta vs \theta error');
	xlabel('odometry \theta (deg)');
	ylabel('\theta error (deg)');
	
	subplot(3,1,3);
	plot(1000*errors(1,:), 1000*errors(2,:), '.k');
	axis('equal');
	title('x,y error');
	xlabel('x errors (mm) ');
	ylabel('y errors (mm) ');
	
end

if false
	figure; hold on;
	for i=1:n
		x1 = o_x(i); y1 = o_y(i);
		x2 = log.sm(1,i); y2 = log.sm(2,i);
		plot([x1 x2],[y1 y2],'r-')
	end
	axis('equal');
end
	
if false
	figure
	hist(rad2deg(o_theta), -5:.2:5);
	title('o_theta');
	figure
	hist(rad2deg(log.sm(3,:)), -5:.2:5);
	title('sm_theta');
	figure
	hist(mod(rad2deg(log.sm(3,:)), 4 * 270/1024), 100);
	title('sm_theta');
end