Now we could calculate the position of the vertices of the aircraft in world coordinates by multiplying each point successively with these four matrices. Since the multiplication of a matrix with a vector is quite expensive (time consuming), one usually takes another path and first multiplies the four matrices together. The multiplication of two matrices is even more expensive, but must be executed only once for the whole object. The multiplications formula_6 and formula_7 are equivalent. Thereafter, the resulting matrix could be applied to the vertices. In practice, however, the multiplication with the vertices is still not applied, but the camera matrices - see below - are determined first.