Copy One Matrix to Another on the TI83 Plus
There are several situations in which you may want to copy the contents of one matrix to another on the TI83 Plus graphing calculator. One of these is when you want to define a new matrix by adding rows and columns to an existing matrix.
To do so, copy the existing matrix to a new matrix and then redefine the new matrix to have the number of rows and columns you desire.
To copy one matrix to another matrix, follow these steps:

If necessary, press [2nd][MODE] to access the Home screen.

Press [2nd][x^{–1}] and key in the number of the matrix you plan to copy.

Press

Press [2nd][x^{–1}] and key in the number of the matrix that will house the copy.
If you copy the contents of a matrix to another matrix, the contents of that other matrix will be erased and replaced with the contents of the matrix you’re copying. If all ten matrices in the Matrix editor are defined and you don’t want to sacrifice any of them in order to make a copy of a matrix, consider saving some of the already defined matrices on your PC.

Press [ENTER] to save a copy of the matrix under the new name.