E-CodeMatrix inverse, exact — a TI-89 Titanium program
MATINV89 is a TI-89 BASIC program for the TI-89 Titanium. Inverse of a 2×2 to 4×4 matrix by Gauss-Jordan on [A | I] in exact fractions, row by row, or SINGULAR when there is none.
What it asks for and what it shows
It asks for 3 values at its prompts. In the example below it shows R1, R2.
Example run
One of its oracle test cases: “2x2”. The inputs are typed in order, and the results are the values the case expects on the screen.
| Step | Value |
|---|---|
| You enter | |
| Input 1 | 2 |
| Input 2 | {4,7} |
| Input 3 | {2,6} |
| The screen shows | |
R1= | {3/5 -7/10} |
R2= | {-1/5 2/5} |
How it's checked
4 test cases, each checked against an independent method. Replayed key by key on a virtual TI-89 Titanium, they make 18 checks.
How E-Code checks every program
Run it or put it on your calculator
- Open the library in the TI-89 Titanium calculator and pick “Matrix inverse, exact” (MATINV89).
- Put it on your own calculator with a computer and a USB cable, or type it in by hand.
Related programs
- Matrix inverse from a typed matrix
- Linear system, exact answers
- LU decomposition with pivoting (exact)
- Quadratic roots, exact when possible
- Fraction calculator: exact, mixed, decimal
All TI-89 Titanium math programs · All TI-89 Titanium programs