# Cosine Similarity

Cosine similarity is a measure of similarity between two vectors of an inner product space that measures the cosine of the angle between them. The cosine of 0° is 1, and it is less than 1 for any other angle. It is defined as follows:

Given two vectors `A`

and `B`

with the same size, calculate the cosine similarity. Return `2.0000`

if cosine similarity is invalid (for example `A = [0]`

and `B = [0]`

).

Example

```
A B Result
[1, 2, 3] [2, 3, 4] 0.9926
[0] [0] 2.0000
```