Adjoint
The matrix formed by taking the transpose of
the
cofactor matrix of a given
original matrix. The adjoint of matrix A is often written adj
A.
Note: This is in fact only one type
of adjoint. More generally, an adjoint of a matrix is any mapping
of a matrix which possesses certain properties. Consult a book
on linear algebra for more information.
Example: 
Find the adjoint of the following matrix:

Solution: 
First find the cofactor of each element.
As a result the cofactor
matrix of A is
Finally the adjoint of A is the transpose of the cofactor
matrix:

See
also
Inverse of a matrix
