MATLAB求马鞍点，代码哪里错了

clear
A=input('please input an array:')
[m,n]=size(A);
for i=1:m
for j=1:n
a=(A(i,j)==min(A(i,:)));
if a
disp(A(i,j))
end
end
end
for c=1:m
b=(A(i,j)<A(c,j))
if b==0
disp(A(i,j))
end
end
B=zeros(m,n);
B(i,j)=A(i,j)
p=length(i)