Function Repository Resource:

UnitMatrix

Get a matrix with a 1 in a selected position and 0s elsewhere

Contributed by: Dennis M Schneider

ResourceFunction["UnitMatrix"][m,n,i,j]

returns an m×n matrix whose only nonzero entry is a 1 in the (i,j)^th position.

ResourceFunction["UnitMatrix"][m,i,j]

returns ResourceFunction["UnitMatrix"][m,m,i,j].

Examples

A 3×4 matrix whose only non-zero entry is a 1 in the (2,3) position:

In[1]:=

Out[1]=

A 5×5 matrix whose only non-zero entry is a 1 in the (4,2) position:

In[2]:=

Out[2]=