# Nullity

In

linear algebra, the

**nullity** of a

matrix *M* is the number of columns of

*M* minus the

rank of

*M*. If the

*m* by

*n* matrix

*M* is regarded as a

linear transformation **R**^{n} →

**R**^{m}, then the nullity is equal to the

dimension of the

kernel of this linear transformation.