Changing the boundary rows and columns.

I'm having a bit of a problem finding a solution to this most likely due to the answer being relatively simple. I have a matrix of all ones. Let's say,

[1,1,1,1; 1,1,1,1; 1,1,1,1] What I need to do is relatively simple. I need to change the values of the first and last columns and rows to zero such that the matrix would be.

[0,0,0,0; 0,1,1,0; 0,0,0,0]

Is there a way to tell matlab to give a value of zero to every number within a given column or row?

Answer 1

[Matt Fig]

A = [1,1,1,1; 1,1,1,1; 1,1,1,1];
A([1,end],:) = 0;  % Changes the first and last row.
A(:,[1,end]) = 0;  % Changes the first and last column.

[Jonathon]

Thanks. I figured such an operation would be relatively simple unfortunately being too simple means few ever think to comment on it.

Answer 2

[Paulo Silva]

m=[1,1,1,1; 1,1,1,1; 1,1,1,1];
m(:,1)=0; %all lines, first column
m(1,:)=0; %all columns, first line
m(:,size(m,2))=0; %all lines, last column
m(size(m,1),:)=0; %all columns, last line