Suppose I want to find the orthogonal projection of (x1,x2,y1,y2) such that x1=x2, y1=y2. I have to calculate the A matrix whose columns are the basis vectors of given subspace. I choose A=[v1;v2] as basis vector combination, where v1=[1 0 1 0] and v2=[0 1 0 1]. Then I calculated the Projection matrix as P=A(AT A)-1A.
Now if I want to find the Projection matrix of (x1,x2,x3,y1,y2,y3,z1,z2,z3) such that
(x2−x1)2+(y2−y1)2+(z2−z1)2=64
(x2−x3)2+(y2−y3)2+(z2−z3)2=36
(x3−x1)2+(y3−y2)2+(z3−z1)2=100
Do I have to find the basis vector for calculating Projection matrix? If yes, how?
Is there any other way to find its Projection matrix (P)?