There are many different types of matrix, many of which you will not come across at GCSE level. The most important matrix operations are those already contained in this section, there is one particular matrix worthy of special mention, that is the "identity" matrix.


This is a special type of matrix, multiplying a matrix by the identity matrix leads the first matrix unchanged if the product exists*.The structure of the identity matrix is as shown below, a square matrix of any dimensional whose elements are 0 except for the primary diagonal where each element has a value of 1.


* Usually denoted like this:


AI = A





Although the identity of the "identity" matrix is normally just a single capital "I", it can be subscripted with the size of the matrix as shown in these examples (2 and 3).