PT
发帖数: 148 | 1 A question puzzles me.
For a cubic curve
y(x) = ax^3 + bx^2 + cx + d
we want to find the inflexion point.
We differentiate the equation with respect to x twice to obtain
y'' = 6ax + 2b
Since at inflexion point, curvatures change signs, i.e. y'' = 0.
then
6ax + 2b = 0 ----> x = -b/(3a)
which means we have only one inflexion point for cubic curves.
However, in a website, it is said for cubic Bezier curves, there are at most
two inflexion points.
Why is that?
Thank you. |
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