'closeness' of multiple vectors

Is there a way to compute how 'closely' a data vector matches another? For example:

A = [1 2 3 4 5];

B = [1 2 3 4 5];
C = [6 7 8 9 10];

Can I use vector A to compare the closeness against vector B, and then vector C? For (A,B), the closeness should be 100%, where as for (A,C) it should be 0%...

Answer 1

[Richard Brown]

Is closeness a measure of how many entries match in matching positions? In this case:

closeness = @(x, y) nnz(x == y) / numel(x);
A = [1 2 3 4 5];
B = [1 2 3 4 5];
C = [6 7 8 9 10];
closeness(A, B)
closeness(A ,C)

If your vectors can have noninteger entries, then to mitigate against floating point errors you'd replace x == y with abs(x - y) < tol * abs(x) where tol is something small, like 1e-14.

[Walter Roberson]

closeness = @(x,y) mean(x(:)==y(:));

[Richard Brown]

haha, yes that's better :)

[Philip]

That's perfect! Thanks to you both for your quick answers!!