如何在MatLab中找到曲线上某点的法线向量

问题描述：

我有一条曲线，我想在这条曲线的给定点上找到法线向量，后来我必须找到该法线向量与另一个向量的点积.

I have a curve and I want to find the normal vector at a given point on this curve, later I have to find the dot product of this normal vector with another vector.

我尝试了MatLab的梯度函数，但是当我们仍然需要确定特定点的梯度时，我猜想它是行不通的.

I tried the gradient function of MatLab, but I guess it doesnt work when we need to find the gradient at a specific point still I am not sure if I am wrong.

请指导我如何在MatLab中实现这一目标.

Please guide me how can I achieve this in MatLab.

谢谢.

答

使用此

如果定义dx = x2-x1和dy = y2-y1，则法线为(-dy，dx)和(dy，-dx).

if we define dx=x2-x1 and dy=y2-y1, then the normals are (-dy, dx) and (dy, -dx).

这是使用y = x^2

x = 0:0.1:1;
y = x.*x;
dy = gradient(y);
dx = gradient(x);
quiver(x,y,-dy,dx)
hold on; plot( x, y)

给出:

PS: 抱歉，切线示例！！！赶时间.感谢Schorsch和Shawn314！

PS: Sorry about the tangential example!!! Got in a hurry. Thanks to Schorsch and Shawn314!

如何在MatLab中找到曲线上某点的法线向量

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