Vector Projection
The projection of vector a onto vector b is the component of a in the direction of b. The calculator returns the scalar projection comp_b(a), the vector projection proj_b(a) = ((a·b)/|b|²) b, and the perpendicular component a − proj_b(a).
Frequently asked questions
What is the difference between scalar projection and vector projection?
The scalar projection comp_b(a) = (a·b)/|b| is a single number giving how far a extends along b. The vector projection proj_b(a) is the actual vector in the direction of b with that length.
What if b is the zero vector?
The projection is undefined — there is no direction to project onto. The calculator reports an error in that case.
What is the perpendicular component used for?
The decomposition a = proj_b(a) + (a − proj_b(a)) splits a into a part parallel to b and a part perpendicular to b — the basis of Gram-Schmidt orthogonalisation.