MATLAB: -1 and 1 matrix

matrix of 1 and -1

Hello All,
 I want to create a  n X n matrix with 1row 1, 2nd row -1, 3rd row 1 , 4th row -1 and so on..... can anyone please guide me .......... thanks.........

Best Answer

Method One:
>> N = 5;
>> 2*mod(ndgrid(1:N,1:N),2)-1
ans =
   1     1     1     1     1
  -1    -1    -1    -1    -1
   1     1     1     1     1
  -1    -1    -1    -1    -1
   1     1     1     1     1
Method Two:
>> 2*(ones(N,1)*mod(1:N,2)).'-1
ans =
   1     1     1     1     1
  -1    -1    -1    -1    -1
   1     1     1     1     1
  -1    -1    -1    -1    -1
   1     1     1     1     1
Method Three:
>> repmat(2*mod(1:N,2).'-1,1,N)
ans =
   1     1     1     1     1
  -1    -1    -1    -1    -1
   1     1     1     1     1
  -1    -1    -1    -1    -1
   1     1     1     1     1
Related Question