A minor is the reduced determinant of a determinant expansion that is formed by omitting the th row and th column of a matrix . So, for example, the minor of the above matrix is given by
The th minor can be computed in the Wolfram Language using
Minor[m_List?MatrixQ, {i_Integer, j_Integer}] := Det[Drop[Transpose[Drop[Transpose[m], {j}]], {i}]]
The Wolfram Language's built-in Minors[m] command instead gives the minors of a matrix obtained by deleting the st row and st column of , while Minors[m, k] gives the th minors of . The Minor code above therefore corresponds to th entry of
MinorMatrix[m_List?MatrixQ] := Map[Reverse, Minors[m], {0, 1}]
i.e., the definition Minors[m, i, j] is equivalent to MinorMatrix[m][[i, j]].