Representation of precomputed data for calculating the upper triangle of the derivative of the covariance matrix of inducing inputs.

calc_shared_upper kernel inducing

• returns

  the pair (eval, upper), where eval is the upper triangle of the covariance matrix of inducing inputs for kernel, and upper is the precomputed data needed for taking derivatives.

calc_deriv_upper upper hyper

• returns

  the derivative of the (symmetric) covariance matrix of inducing inputs given precomputed data upper and the hyper-variable.