Editing Row and column spaces (section)

===Dimension===
{{main|Rank (linear algebra)}}
The [[dimension (linear algebra)|dimension]] of the row space is called the '''[[rank (linear algebra)|rank]]''' of the matrix.  This is the same as the maximum number of linearly independent rows that can be chosen from the matrix, or equivalently the number of pivots.  For example, the 3&nbsp;×&nbsp;3 matrix in the example above has rank two.<ref name="example"/>

The rank of a matrix is also equal to the dimension of the [[column space]].  The dimension of the [[null space]] is called the '''nullity''' of the matrix, and is related to the rank by the following equation:
:<math>\operatorname{rank}(A) + \operatorname{nullity}(A) = n,</math>
where {{mvar|n}} is the number of columns of the matrix {{mvar|A}}.  The equation above is known as the [[rank–nullity theorem]].