www.pudn.com > trackingdemos.zip > plot_chi2.m

function fig = plot_chi2(track) 
 
% chi2 region vs. time 
[nx, ny] = size(track(1).NEES); 
fig = figure; 
subplot(2,2,1); 
hold on; 
for i=1: ny 
    index(i).ind = []; 
    for j=1:nx 
        if track(1).NEES(j,i)<13.3   % 99% uppper bound, 4df 
            if i>1 
                if ~isempty(find(~(index(i-1).ind-j))) 
                    index(i).ind = [index(i).ind, j]; 
                end 
            else 
                index(i).ind = [index(i).ind, j]; 
            end 
        end 
    end 
    n(i) = length(index(i).ind); 
    lower = chi2inv(.025, n(i)*4)/n(i); 
    upper = chi2inv(.975, n(i)*4)/n(i); 
    plot(i, lower, 'r.'); 
    plot(i, upper, 'r.'); 
    plot(i, mean(track(1).NEES(index(i).ind, i)), 'k.-'); 
end 
xlabel('scans'); 
ylabel('Test statistic (NEES) and the 95% \chi^2 region'); 
title('NEES, target 1, excluding lost tracks'); 
hold off; 
 
subplot(2,2,2) 
hold on; 
for i=1:ny 
    index(i).ind = []; 
    for j=1:nx 
        if track(2).NEES(j,i)<13.3   % 99% uppper bound, 4df 
            if i>1 
                if ~isempty(find(~(index(i-1).ind-j))) 
                    index(i).ind = [index(i).ind, j]; 
                end 
            else 
                index(i).ind = [index(i).ind, j]; 
            end 
        end 
    end 
    n(i) = length(index(i).ind); 
    lower = chi2inv(.025, n(i)*4)/n(i); 
    upper = chi2inv(.975, n(i)*4)/n(i); 
    plot(i, lower, 'r.'); 
    plot(i, upper, 'r.'); 
    plot(i, mean(track(2).NEES(index(i).ind, i)), 'k.-'); 
end 
xlabel('scans'); 
ylabel('Test statistic (NEES) and the 95% \chi^2 region'); 
title('NEES, target 2, excluding lost tracks'); 
hold off; 
 
lower = chi2inv(.025, nx*4)/nx; 
upper = chi2inv(.975, nx*4)/nx; 
tl = linspace(lower, lower, ny); 
tu = linspace(upper, upper, ny); 
subplot(2,2,3) 
hold on; 
plot(tl, 'r.'); 
plot(tu, 'r.'); 
plot(mean(track(1).NEES), 'k.-'); 
xlabel('scans'); 
ylabel('Test statistic (NEES) and the 95% \chi^2 region'); 
title('NEES, target 1, including lost tracks'); 
hold off; 
 
subplot(2,2,4) 
hold on; 
plot(tl, 'r.'); 
plot(tu, 'r.'); 
plot(mean(track(2).NEES), 'k.-'); 
xlabel('scans'); 
ylabel('Test statistic (NEES) and the 95% \chi^2 region'); 
title('NEES, target 2, including lost tracks'); 
hold off;