E-CodePratt truss by the method of sections, step by step — a TI-89 Titanium program
PRATT89 is a TI-89 BASIC program for the TI-89 Titanium. A Pratt bridge truss with n panels, equal loads at the bottom joints and supports at both ends. Cut any panel: the support reactions, the three section equations (ΣFx, ΣFy, ΣM) written out with your numbers, all three solved at once by the TI-89's algebra system, and each cut member's force marked T (tension) or C (compression).
What it asks for and what it shows
It asks for 5 values at its prompts. In the example below it shows RA kN, top ft kN(C), bottom fb kN(T), diag fd kN(T), 1 REACTIONS, 3 SOLVE ALL 3 (CAS), 4 ANSWER, PANEL 2.
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 | 6 |
| Input 2 | 4 |
| Input 3 | 4 |
| Input 4 | 10 |
| Input 5 | 2 |
| The screen shows | |
RA kN= | 25 |
top ft kN(C)= | -40 |
bottom fb kN(T)= | 25 |
diag fd kN(T)= | 21.21320344 |
| Text | 1 REACTIONS |
| Text | 3 SOLVE ALL 3 (CAS) |
| Text | 4 ANSWER, PANEL 2 |
How it's checked
5 test cases, each checked against an independent method. Replayed key by key on a virtual TI-89 Titanium, they make 45 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 “Pratt truss by the method of sections, step by step” (PRATT89).
- Put it on your own calculator with a computer and a USB cable, or type it in by hand.
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All TI-89 Titanium engineering programs · All TI-89 Titanium programs