The UnitVector(i, d) command returns a d-dimensional Vector in which the ith entry is one and all other entries are zero.

The UnitVector[row](i, d) command behaves like UnitVector(i, d) except that a row Vector is returned.  If the orientation option is omitted or if UnitVector[column](i, d) is used, a column Vector is returned.

$\mathrm{with}\left(\mathrm{Student}\left[\mathrm{LinearAlgebra}\right]\right)\:$

$\mathrm{UnitVector}\left(4\,5\right)$

$\left[\begin{array}{c}0\\ 0\\ 0\\ 1\\ 0\end{array}\right]$

$\mathrm{UnitVector}\left[\mathrm{row}\right]\left(1\,3\right)$

$\left[\begin{array}{ccc}1& 0& 0\end{array}\right]$