# What is Vector.AlmostEqualTo and Vector.IsParallel?

Vector in one of the most important factor of geometry when you manipulate geometries with Dynamo.

If so, Here is a question.

As known, a vector has two factors in it. One is Direction, another is Length.

I wondered what does ‘Almost’ means In Vector.AlmostEqualTo node. There is no Almost kind of things in Math. There are only Right or Wrong.

So, I’ve tested the node with some vectors which are Almost Equal (for me) to each other to find out what ‘Almost’ means in the node.

1. Almost Equal Length

As you can see above, 1 and 1.09 are almost equal length. But 1 and 1.1 are totally different length. It means under 10% longer lengths are regarded as Almost Equal.

2. Almost Equal Angle

According to the test, under 5.74 degree difference is Almost Equal and others are totally different angle for the node. And of course 180 degree difference is also totally different angle.
So, if you want to take ‘Almost Equal Angle’ while ignoring Length of both, you can…