Returns the analytical gradient of leaveOneOutFun.
leaveOneOutGrad(param, model, envir)a vector containing the optimization variables.
an object of class km.
an environment specifying where to get intermediate values calculated in leaveOneOutFun.
the gradient of leaveOneOutFun at param.
F. Bachoc (2013), Cross Validation and Maximum Likelihood estimations of hyper-parameters of Gaussian processes with model misspecification. Computational Statistics and Data Analysis, 66, 55-69. http://www.lpma.math.upmc.fr/pageperso/bachoc/publications.html
O. Dubrule (1983), Cross validation of Kriging in a unique neighborhood. Mathematical Geology, 15, 687-699.