Fig. 5

Cost function with respect to parameter changes in the numerical experiments. a–d Cost functions in Exp. 1 as a function of each frictional parameter of a A, b A–B, and c L, and d the enlarged view of the horizontal axis of c. The color of each line corresponds to the number of region shown in Fig. 2a. Stars and circles indicate the optimum and true frictional parameters with corresponding colors. e–h Same as a–d, but for Exp. 2