How to find the projection of vectors from corrdinates?

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!

[Dyuman Joshi]

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]

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.

Answer 1

[Dyuman Joshi]

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

[Karl Bridggie]

Thank you @Dyuman Joshi! I didn't know we could define the vectors that way.