matrix

an $\text{[math]}$ matrix is a rectangular array of entries, $\text{[math]}$ high and $\text{[math]}$ wide. we denote by $\text{[math]}$ the set of $\text{[math]}$ matrices.
[cite:@calc_hubbard_2015 definition 1.2.1]

we use capital letters to denote matrices. usually our matrices will be arrays of numbers, real or complex, but matrices can be arrays of polynomials, or of more general functions; a matrix can even be an array of other matrices. a vector $\text{[math]}$ is an $\text{[math]}$ matrix; a number is a $\text{[math]}$ matrix.
[cite:@calc_hubbard_2015 chapter 1.2 introducting the actors: matrices]

a matrix can be constructed over a specific finite/infinite set of numbers. for example $\text{[math]}$ which is the set of integers, when we say a matrix is over a specific field of numbers we mean that the numbers in the matrix are limited to that field of numbers

consider this matrix over the field $\text{[math]}$ , where all the numbers are integers
src_sage{ld(random_matrix(ZZ,5,4))} {{{results( $\text{[math]}$ )}}}