rank of a unit identity matrix of order 4 is
Identity matrix The identity matrix of a given size is the only idempotent matrix of that size having full rank. That is, it is the only matrix such that (a) when multiplied by itself the result is itself, and (b) all of its rows, and all of its columns, are linearly independent.
I Am Number Four A prelude of the killing of one of the Garde children—No. 3—by Mogadorians. This story is about a 15-year-old boy named John Smith. He has been on the run from the age of 4, and he is from a planet called Lorien.