How to find the scalar multiple of two vectors?

Example; a=[1;2;3] and b=[2;4;6], hence the lambda is 2.

Answer 1

[James Tursa]

E.g., (with some accounting for potential 0 values)

d = b ./ a;
result = mean(d(~isnan(d)));

This is naive code that assumes the same scalar applies to all elements. If it is possible that is not the case, you would need to tell us how to handle the situation.