In mathematics, a submatrix is a matrix formed by selecting certain rows and columns from a bigger matrix. That is, as an array, it is cut down to those entries constrained by row and column.
For example
Then
![A[1,2; 1,3,4]=\begin{bmatrix} a_{11} & a_{13} & a_{14} \\ a_{21} & a_{23} & a_{24} \end{bmatrix}](a/../upload/math/a635b082b4b534a7cf905dd657f20557.png)
is a submatrix of A formed by rows 1,2 and columns 1,3,4. This submatrix can also be denoted by A(3;2) which means that it is formed by deleting row 3 and column 2.
The above two methods are common, but there is no standard way to denote a submatrix.
The corresponding concept in determinant theory is of minor determinant, that is, determinant of a square submatrix.
See also: block matrix.