E-CodeGaussian elimination with row operations — a TI-84 Plus CE program
GAUSSJ is a TI-BASIC program for the TI-84 Plus CE. Type 2 to 5 equations as rows of the augmented matrix. It shows the work: at each column the pivot and any row swap (partial pivoting), every row operation Ri-M*Rk→Ri with its multiplier, the matrix after each column, then back substitution, the solution and the determinant.
What it asks for and what it shows
It asks for 4 values at its prompts. In the example below it shows X1, X2, X3, DET, COLUMN 1, SWAP R1,R2, PIVOT, R2 M, R3 M, COLUMN 2, SWAP R2,R3, PIVOT, R3 M, COLUMN 3, NO SWAP, PIVOT, BACK SUBSTITUTE, SOLUTION (IN L.
Example run
One of its oracle test cases. The inputs are typed in order, and the results are the values the case expects on the screen.
| Step | Value |
|---|---|
| You enter | |
| Input 1 | 3 |
| Input 2 | {2,1,-1,8} |
| Input 3 | {-3,-1,2,-11} |
| Input 4 | {-2,1,2,-3} |
| The screen shows | |
X1= | 2 |
X2= | 3 |
X3= | -1 |
DET= | -1 |
| Text | COLUMN 1 |
| Text | SWAP R1,R2 |
PIVOT= | -3 |
R2 M= | -.66667 |
R3 M= | .66667 |
| Text | COLUMN 2 |
| Text | SWAP R2,R3 |
PIVOT= | 1.6667 |
R3 M= | .2 |
| Text | COLUMN 3 |
| Text | NO SWAP |
PIVOT= | .2 |
| Text | BACK SUBSTITUTE |
| Text | SOLUTION (IN L |
How it's checked
5 test cases, each checked against an independent method. Replayed key by key on a virtual TI-84 Plus CE, they make 110 checks.
How E-Code checks every program
Run it or put it on your calculator
- Open the library in the TI-84 Plus CE calculator and pick “Gaussian elimination with row operations, step by step” (GAUSSJ).
- Put it on your own calculator with a computer and a USB cable, or type it in by hand.
Related programs
- LU decomposition with partial pivoting
- Linear system solver (n equations)
- Matrix toolkit: det, inverse, product, power, transpose
- Vectors: dot, cross, angle, projection
- Eigenvalues and eigenvectors (2×2, 3×3)
All TI-84 Plus CE math programs · All TI-84 Plus CE programs