Replace A[x] with f(x) and done. A modified binary search called ternary search is well known used to find when derivative = 0, numerically. https://en.m.wiki

Replace A[x] with f(x) and done. A modified binary search called ternary search is well known used to find when derivative = 0, numerically. https://en.m.wikipedia.org/wiki/Ternary_search https://en.m.wikipedia.org/wiki/Ternary_search