In linear algebra, the column space (also called the range or image) of a matrix A is the span (set of all possible linear combinations) of its column vectors. The column space of a matrix is the image or range of the corresponding matrix transformation.
Let F {\displaystyle F} be a field. The column space of an m × n matrix with components from F {\displaystyle F} is a linear subspace of the m-space F m {\displaystyle F^{m}} . The dimension of the column space is called the rank of the matrix and is at most min(m, n). A definition for matrices over a ring R {\displaystyle R} is also possible.
The row space is defined similarly.
The row space and the column space of a matrix A are sometimes denoted as C(AT) and C(A) respectively.
This article considers matrices of real numbers. The row and column spaces are subspaces of the real spaces R n {\displaystyle \mathbb {R} ^{n}} and R m {\displaystyle \mathbb {R} ^{m}} respectively.