function [X]=cofact(A,m,n)
[a,b]=size(A);
if m>a | n>b | (a~=b)
    error('Index exceeds matrix dimensions or matrix is not square. Word.')
end
c=1;
for k=1:a
    if k ~= m
        B(c,:)=[A(k,1:(n-1)), A(k,(n+1):b)];
        c=c+1;
    end
end
X=(-1)^(m+n)*det(B);
return;