Deprecated since version 4.0: The parabolic_turning_point function is deprecated and may be removed in version 4.1. Use
Find the location of the turning point for a parabola
y(x) = ax^2 + bx + c, given input values
y(-1), y(0), y(1). The maximum is located at
x0 = -b / 2a. Assumes that the input array represents an equally spaced sampling at the locations
y(-1), y(0) and y(1).