What are the best practices for floating-point comparisons in Matlab?

Question

Obviously, float comparison is always tricky. I have a lot of assert-check in my (scientific) code, so very often I have to check for equality of sums to one, and similar is

Answer 1

Any fixed tolerance will fail if you put in very large or very small numbers, simplest solution is to use eps to get the double precision:

abs(A-B)

The 4 is a totally arbitrary number, which is sufficient in most cases.