Module kernel 

Kernel expressions for automatic kernel structure discovery.

Provides a closed grammar of base kernels and composite expressions formed by sum and product operators. Each KernelExpr can be evaluated at a pair of scalar inputs and described as a human-readable string.

Base kernels

Variant	Formula
Rbf	exp(-‖x-y‖² / (2 ℓ²))
Matern52	(1 + √5·r/ℓ + 5r²/(3ℓ²)) exp(-√5·r/ℓ)
Periodic	exp(-2 sin²(π‖x-y‖/p) / ℓ²)
Linear	σ² · x · y
WhiteNoise	σ² · 𝟙{x == y}

Enums

BaseKernel

One of the atomic kernel functions in the grammar.

KernelExpr

A compositional kernel expression formed by summing or multiplying sub-kernels.

Functions

base_kernels

Enumerate all base kernels with initial hyperparameters.