Squared Exponential Kernel

## Arguments

- x
A vector (or matrix if vectorized = T) of inputs.

- y
A vector (or matrix if vectorized = T) of inputs.

- hp
A tibble, data frame or named vector, containing the kernel's hyperparameters. Required columns: 'se_variance', 'se_lengthscale'.

- deriv
A character, indicating according to which hyper-parameter the derivative should be computed. If NULL (default), the function simply returns the evaluation of the kernel.

- vectorized
A logical value, indicating whether the function provides a vectorized version for speeded-up calculations. If TRUE, the

`x`

and`y`

arguments should be the vector or matrix containing all inputs for which the kernel is evaluated on all pairs of elements. If FALSE, the`x`

and`y`

arguments are simply two inputs.