How to make one element in a matrix the same for other elements?

What I mean by the question is the following:

Say I have matrix A and my A(2,1) = constant

Is there a way that I can write A(2,1)=A(2,1)=A(2,3) and so on?

[CS Researcher]

Can you explain a bit more? What exactly are you trying to do?

[Bryan Galindo]

What I'd like to do is have one element be the same value for various other elements.

The bigger picture of what I am trying to do however, is somewhat of a diagonal 11x11 matrix.

The A(1,1) and A(11,11) are their own unique values. (The first and last elements)

The middle rows in the diagonal (k=0) is X And the 2 other diagonals (k=1 & k=-1) is y

Example if it were a 4x4

A =

8 y 0 0

y x y 0

0 y x y

0 0 y 10

Sorry, I know it's a bit confusing.

Answer 1

[Stephen23]

>> x = 1;
>> y = 2;
>> N = 4; % size of the matrix
>> A = eye(N) * x;
>> A(1+1:1+N:end) = y;
>> A(1+N:1+N:end) = y;
>> A(1) = 8;
>> A(end) = 10
A =
     8     2     0     0
     2     1     2     0
     0     2     1     2
     0     0     2    10

[Bryan Galindo]

THANK YOU. Exactly what I was looking for.

[Bryan Galindo]

Actually I have another question.

I have a 1xn matrix that have specific values at the ends but the middle values are all the same. How could I do this?

For example

C =

5

x

x

x

x

10

[Stephen23]

One solution:

C = ones(1,n) * x;
C(1) = 5;
C(end) = 10;

or you could try:

C = [5,x*ones(1,n-2),10]

note that these have different outputs for n<3.

Answer 2

[Roger Stafford]

You want every other element in the second row to be set equal to the first element?

   A(2,:) = A(2.1);

Or do you have other elements to be set? Your description is not very clear.