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

I have had good experience with xUnit, a unit test framework for Matlab. After installing it, you can use:

• assertVectorsAlmostEqual(a,b) (checks for normwise closeness between vectors; configurable absolute/relative tolerance and sane defaults)
• assertElementsAlmostEqual(a,b) (same check, but elementwise on every single entry -- so [1 1e-12] and [1 -1e-9] will compare equal with the former but not with the latter).

They are well-tested, fast to use and clear enough to read. The function names are quite long, but with any decent editor (or the Matlab one) you can write them as assertV.