A =

  Columns 1 through 6

           1           0           0           0           0           0
           1           1           1           1           1           1
           1           2           4           8          16          32
           1           3           9          27          81         243
           1           4          16          64         256        1024
           1           5          25         125         625        3125
           1           6          36         216        1296        7776

  Column 7

           0
           1
          64
         729
        4096
       15625
       46656

>> B=[1;3;2;1;3;2;1]

B =

     1
     3
     2
     1
     3
     2
     1 

>> [N N]=size(A);
>> X=zeros(N,1);
>> C=zeros(1,N+1);
>> Aug= [A B];
>> for p=1:N-1
  [Y,j] =max(abs(Aug(p:N,p)));
  C=Aug(p,:);
  Aug(p,:)=Aug(j+p-1,:);
  Aug(j+p-1,:)=C;
  if Aug(p,p)==0
     'A was singluar. No unique solution'
      break
   end
for k=p+1:N
   m=Aug(k,p)/Aug(p,p);
   Aug(k,p:N+1) =Aug(k,p:N+1)-m*Aug(p,p:N+1);
 end
end
>> X=backsub(Aug(1:N,1:N),Aug(1:N,N+1));
>> X

X =

    1.0000
   -1.8000
   11.0250
  -10.5625
    3.9375
   -0.6375
    0.0375

>>    >> format long
>> X

X =

   1.00000000000000
  -1.80000000000011
  11.02500000000004
 -10.56250000000001
   3.93750000000000
  -0.63750000000000
   0.03750000000000