pdist: Partitioned Distance Function
Computes the euclidean distance between rows of a matrix X
and rows of another matrix Y. Previously, this could be done
by binding the two matrices together and calling 'dist', but
this creates unnecessary computation by computing the distances
between a row of X and another row of X, and likewise for Y.
pdist strictly computes distances across the two matrices, not
within the same matrix, making computations significantly
faster for certain use cases.