How to find the projection of vectors from corrdinates?

Question

Karl Bridggie 2022-9-14

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1804825-how-to-find-the-projection-of-vectors-from-corrdinates

评论： Karl Bridggie 2022-9-15

采纳的回答： Dyuman Joshi

Hi,

If I have the corrdinates of two vectors (not the elements of the vectors) in 2D plane

v1: from (1, 2) to (9, 10)

v2: from (9, 10) to (6, 14)

is there a way to get the projection of v1 on v2?

Thanks a lot for your help!

2 个评论
显示无隐藏无

Dyuman Joshi 2022-9-14

This is a simple mathematics question. Yes, there is a way to get what you want.

But how does this relate to MATLAB?

Is this a homework/assignment problem? If so, what have you tried yet?

Karl Bridggie 2022-9-14

Thanks Dyuman! I know how to do it in maths, and I think I should use the dot function in MATLAB. If the vectors are u and v, then I need to do something like this:

dot(u,v) / dot(v,v) * v;

My problem is I don't know how to convert the vectors in corrdinate format (as v1 and v2 in the question) to the format that is suitable for the dot function.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Dyuman Joshi 2022-9-14

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1804825-how-to-find-the-projection-of-vectors-from-corrdinates#answer_1053270

Proceed the same way as you would on pen and paper. You can use points to define the vector -

%[x-coordinate y-coordinate]
p1=[1 2];
p2=[9 10];
p3=[9 10];
p4=[6 14];
%defining vectors
v1=p2-p1;
v2=p4-p3;
%Therefore, projection of v1 on v2 is
projv1_v2=dot(v1,v2)/dot(v2,v2)*v2
projv1_v2 = 1×2
   -0.9600    1.2800