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The unit indexing function can be used to construct 1-dimensional rtable objects of type Array or Vector .

In the construction of a Vector, the unit[j] indexing function specifies a Vector which has the value 1 for entry j and the value 0 everywhere else.

The specification in the construction of a 1-dimensional Array is similar.

If an object is defined by using the unit indexing function, its elements cannot be reassigned.

Under normal circumstances, no storage is allocated for the entries of an object constructed by using the unit indexing function.

$A≔\mathrm{Array}\left(\mathrm{unit}\left[2\right]\,1..3\right)$

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

$V≔\mathrm{Vector}\left(4\,\mathrm{shape}=\mathrm{unit}\left[3\right]\right)$

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

$V\left[2\right]≔3$

Error, unit vector can only have one non-zero entry