How to plot error for 2 different point matlab

Hello everyone,

today I need your help because I am confused with the calculation of an error :

I have (for example) 50 points that represent particle. I have calculated these points' centroid with two methods. So I have two pairs of vector i1;j1 (size(i1)=size(j1)=1 50) and i2;j2 (size(i2)=size(j2)=1 50). i1;j1 represent the centroids found with the first method and i2;j2 the centroids found with the second method.

I know that the good method is the first method, so i1;j1 represent the right centroids.

My question is : how can I find the error between i1;j1 and i2;j2 (I mean if i1(1)=0 and j1(1)=0 and i2(1)=0.05 and j2(1)=0.1 there are an error concerning i and j).

My second question is : how can I plot these errors in a 2D plan so that errors are drawn to the position of particles. And give them a color proportional to the intensity?

Thank you.

[Walter Roberson]

I think this might be the same question as http://www.mathworks.com/matlabcentral/answers/285604-calcul-d-erreur-de-vitesse ?