referencing a matrix value to another matrix value within the same matrix

How do I essentially do the following

A = [ 1 2 3 A(1,1)];

Where I want the first row fourth column to equal the value from the first row first column which is already defined.

I get an error when I try to do this

Answer 1

[madhan ravi]

A = [1 2 3];
A = [ 1 2 3 A(1,1)];  % to perform A(1,1) it has to be defined before using

[madhan ravi]

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