E-CodeLinear system solver (n equations) — a TI-84 Plus CE program
LINSYS is a TI-BASIC program for the TI-84 Plus CE. Solves 2 to 6 linear equations in as many unknowns from typed rows {a1,...,an,b}; says NO SOLUTION or INFINITELY MANY (with the rank) instead of failing, and prints the residual as a check.
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, RESID.
Example run
One of its oracle test cases: “3x3 textbook”. 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 |
RESID= | 0 |
How it's checked
8 test cases, each checked against an independent method. Replayed key by key on a virtual TI-84 Plus CE, they make 41 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 “Linear system solver (n equations)” (LINSYS).
- Put it on your own calculator with a computer and a USB cable, or type it in by hand.
Related programs
- Matrix toolkit: det, inverse, product, power, transpose
- LU decomposition with partial pivoting
- Eigenvalues and eigenvectors (2×2, 3×3)
- Vectors: dot, cross, angle, projection
- Quadratic formula solver
All TI-84 Plus CE math programs · All TI-84 Plus CE programs