[source] # Cosine Cosine Similarity is a measure that ignores the magnitude of the distance between two non-zero vectors thus acting as strictly a judgement of orientation. Two vectors with the same orientation have a cosine similarity of 1, whereas two vectors oriented at 90° relative to each other have a similarity of 0, and two vectors diametrically opposed have a similarity of -1. To be used as a distance function, we subtract the Cosine Similarity from 1 in order to satisfy the positive semi-definite condition, therefore the Cosine *distance* is a number between 0 and 2. $$ {\displaystyle {\text{Cosine}}=1 - {\mathbf {A} \cdot \mathbf {B} \over \|\mathbf {A} \|\|\mathbf {B} \|}=1 - {\frac {\sum \limits _{i=1}^{n}{A_{i}B_{i}}}{{\sqrt {\sum \limits _{i=1}^{n}{A_{i}^{2}}}}{\sqrt {\sum \limits _{i=1}^{n}{B_{i}^{2}}}}}}} $$ **Data Type Compatibility:** Continuous ## Parameters This kernel does not have any parameters. ## Example ```php use Rubix\ML\Kernels\Distance\Cosine; $kernel = new Cosine(); ```