[Bf-python] Vector Comparison Issue

[Jonathan Merritt]

Campbell Barton wrote:

> from Blender import Mathutils
> f = 22.0 / 7.0
> vec = Mathutils.Vector(f,0,0)
> print vec.x == f
> ...False


I suppose it's an example of the general rule: "Never do floating point 
equality comparisons!"

The general way around this is to check equality up to a reasonable 
limit: epsilon.  When epsilon is a small number greater than zero:
    equal = ((vec.x + epsilon) >= f) and ((vec.x - epsilon) <= f)

Why do you want to check for floating-point equality to begin with 
though?  Can't you establish "logical equality", between objects or maps 
of objects, rather than "numerical equality"?

Jonathan Merritt.