Figure 7.

Examples of the two Hodgkin–Huxley model oscillations obtained with different external currents I_ext. (a) Dependency between f_l and f_h with t. (b–f) The high-fidelity function (the yellow curve) versus posterior means with 2 standard deviations (dashed lines) of 5 compared methods with 20 high-fidelity data points and 300 uniformly distributed low-fidelity data points. (b) GP (Kriging) and low-fidelity data (the red-dashed curve). (c) Auto-regressive GP (AR1 or coKriging). (d) Nonlinear auto-regressive GP (NARGP). (e) GP in the four-dimensional space (GP+E), using (t, f_l(t), f_l(t − τ), f_l(t − 2τ)). (f) GP in the six-dimensional space (GP+E(2)), using (t, f_l(t), f_l(t − τ), f_l(t − 2τ), f_l(t − 3τ), f_l(t − 4τ)). (Online version in colour.)