} else if (min_diff > 0 && max_diff < 0) {
XBT_CWARN(surf_lagrange_dichotomy,
"The impossible happened, partial_diff(min) > 0 && partial_diff(max) < 0");
} else if (min_diff > 0 && max_diff < 0) {
XBT_CWARN(surf_lagrange_dichotomy,
"The impossible happened, partial_diff(min) > 0 && partial_diff(max) < 0");