'Return the (i,j) minor of `self`.  That is,
return the determinant of the matrix obtained by deleting
the `i`th row and `j`th column from `self`.
See Also
minor_submatrix
cofactor
det'

def minor(self, i, j, method='berkowitz'):

    if ((self.rows != self.cols) or (self.rows < 1)):
        raise NonSquareMatrixError()
    return self.minor_submatrix(i, j).det(method=method)
