Generic implementation of the Sobol G-function for k inputs.
Columns of X are interpreted as inputs X1, X2, ..., Xk.
sobol_g_function(X, a = c(0, 1, 4.5, 9, 99, 99, 99, 99))Numeric vector of length nrow(X) with model outputs.
Numeric matrix or data.frame of inputs in [0, 1].
Numeric vector of parameters a_j controlling importance.
Its length must be at least ncol(X).