Create main diagonal with repeated numbers but one exception

Hello. Im new to Matlab and programming in general so i hope this is not to dumb.

I want to create a main diagonal line to my ones(5) matrix.

The diagonal should contain the first number as 1 and the rest are all 2.

Like this:

     1     1     1     1     1
     1     2     1     1     1
     1     1     2     1     1
     1     1     1     2     1
     1     1     1     1     2

Since we are also supposed to construct bigger matrices of the same kind, i would like to be able to get a "repeat" on the number 2 so i dont have to write all of them out.

I have only been able to construct a diagonal that changes ALL the values with 2 by doing like this:

     M = ones(5);
     u = 2;
     v = repmat(u,5,1);
     M = M - diag(diag(M)) + diag(v)
     
     2     1     1     1     1
     1     2     1     1     1
     1     1     2     1     1
     1     1     1     2     1
     1     1     1     1     2

So i need some way to get 1 instead of 2 in position (1,1). Is it possible to somehow integrate that into v or somewhere else and still keep the 'repmat'?

Thank you.

Answer 1

[JESUS DAVID ARIZA ROYETH]

solution:

n=5;
M=diag([0 ones(1,n-1)])+ones(n)

[Jonas]

Thank you very much!