Section TI83  Texas Instruments 83

Contributed by  Douglas Phelps
On the TI-83, press the MATRX key. Press the right arrow key twice so that EDIT is highlighted. Move the cursor down so that it is over the desired letter of the matrix and press ENTER . For example, let’s call our matrix B , so press the down arrow once and press ENTER . To enter a $2\times 3$ matrix, press 2 ENTER 3 ENTER . To create the matrix

press 1 ENTER 2 ENTER 3 ENTER 4 ENTER 5 ENTER 6 ENTER .

Contributed by  Douglas Phelps
Suppose B is the name of a matrix stored in the TI-83. Press the MATRX key. Press the right arrow key once so that MATH is highlighted. Press the down arrow eleven times so that rref ( is highlighted, then press ENTER . to choose the matrix B , press MATRX , then the down arrow once followed by ENTER . Supply a right parenthesis ( ) ) and press ENTER .

Note that this command will not work for a matrix with more rows than columns. (Ed. Not sure just why this is!) A work-around is to pad the matrix with extra columns of zeros until the matrix is square.

Contributed by  Douglas Phelps
Entering a vector on the TI-83 is the same process as entering a matrix. You press 4 ENTER 3 ENTER for a $4\times 3$ matrix. Likewise, you press 4 ENTER 1 ENTER for a vector of size 4. To multiply a vector by 8, press the number 8, then press the MATRX key, then scroll down to the letter you named your vector (A, B, C, etc) and press ENTER .

To add vectors A and B for example, press the MATRX key, then ENTER . Then press the + key. Then press the MATRX key, then the down arrow once, then ENTER . [A] + [B] will appear on the screen. Press ENTER .