What is the matrix format?

Question

Mathematics

In one of the articles I came across such an entry
P = K[I|0]
Where K and P are matrices.
What is it?

Answer 1

I googled a similar formula in one article:
Three matrices are multiplied. The last one (X) has size (4, 1). The square brackets form the matrix (1, 4) from the vector R (1, 3) and the number t, i.e. [r1 r2 r3 t]. The result of the multiplications is a matrix of size (1, 1), i.e. scalar. The matrix K has size (3, 3).