This function is approximately linear on the given domain, but has a slope of zero at the origin (Currin et al., 1988). Currin, C., Mitchell, T., Morris, M., & Ylvisaker, D. (1988). A Bayesian ...

This function is a simple two-dimensional example which occurs several times in the literature on computer experiments. Currin, C., Mitchell, T., Morris, M., & Ylvisaker, D. (1988). A Bayesian ...