w is a vector and v is its reference vector:
Decomposing w into two vectors w||v and w⊥v:
w = w⊥v + w||v
w is perpendicular to v = w⊥v
w is parallel to v =w||v
w⊥v = w-w||v
so to find the parallel vector length, w||v we can use the projection formula:
proj(v)w = Trans(w).v/(Trans(w).w)*w
