MATLAB: Changing elements with a condition

Question

Hi all,

I've some basic questions about changing the elements of a 9×9 matrix with a specific condition. The matrix is;

X1 =

         0         0         0         0         0         0         0         0         0
    0.2778    0.2800         0         0         0         0         0         0         0
    0.2222    0.2000    0.3700         0         0         0         0         0         0
    0.1333    0.1600    0.1750    0.4600         0         0         0         0         0
    0.0889    0.0960    0.1400    0.1500    0.5950         0         0         0         0
    0.0667    0.0640    0.0840    0.1200    0.1125    0.5950         0         0         0
    0.0611    0.0480    0.0560    0.0720    0.0900    0.1125    0.6400         0         0
    0.0444    0.0440    0.0420    0.0480    0.0540    0.0900    0.1000    0.6400         0
    0.0222    0.0320    0.0385    0.0360    0.0360    0.0540    0.0800    0.1000    0.6400

And I want to create X2 as

0  0  0  0  0  0  0  0  0 
  0  0  0  0  0  0  0  0  0 
  0  0.278  0.280  0  0  0  0  0  0 
  0  0.222  0.200  0.370  0  0  0  0  0 
  0  0.133  0.160  0.175  0.460  0  0  0  0 
  0  0.089  0.096  0.140  0.150  0.595  0  0  0 
  0  0.067  0.064  0.084  0.120  0.113  0.595  0  0 
  0  0.061  0.048  0.056  0.072  0.090  0.113  0.640  0 
  0  0.044  0.044  0.042  0.048  0.054  0.090  0.100  0.640 

And X3 as

  0  0  0  0  0  0  0  0  0 
  0  0  0  0  0  0  0  0  0 
  0  0  0  0  0  0  0  0  0 
  0  0  0.278  0.280  0  0  0  0  0 
  0  0  0.222  0.200  0.370  0  0  0  0 
  0  0  0.133  0.160  0.175  0.460  0  0  0 
  0  0  0.089  0.096  0.140  0.150  0.595  0  0 
  0  0  0.067  0.064  0.084  0.120  0.113  0.595  0 
  0  0  0.061  0.048  0.056  0.072  0.090  0.113  0.640 

Thanks to everyone for solution.

;

Answer 1

clear X2 X3
[m,n] = size(X1);
X2(2:m,2:n) = X1(1:m-1,1:n-1);
X3(3:m,3:n) = X1(1:m-2,1:n-2);