E-CodeBode point and stability margins — a TI-84 Plus CE program
BODEPT is a TI-BASIC program for the TI-84 Plus CE. Type a transfer function as numerator and denominator coefficient lists: magnitude, dB and continuous (unwrapped) phase at any frequency, or the gain and phase crossover frequencies with the phase margin and gain margin.
What it asks for and what it shows
It asks for 3 values at its prompts, after you pick option 1 from its menu. In the example below it shows MAG, DB, PHASE D, RE, IM.
Example run
One of its oracle test cases: “1/(s+1) at the corner: -3 dB, -45°”. The inputs are typed in order, and the results are the values the case expects on the screen.
| Step | Value |
|---|---|
| You enter | |
| Menu | option 1 |
| Input 1 | {1} |
| Input 2 | {1,1} |
| Input 3 | 1 |
| The screen shows | |
MAG= | 0.7071067812 |
DB= | -3.010299957 |
PHASE D= | -45 |
RE= | 0.5 |
IM= | -0.5 |
How it's checked
9 test cases, each checked against an independent method. Replayed key by key on a virtual TI-84 Plus CE, they make 51 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 “Bode point and stability margins” (BODEPT).
- Put it on your own calculator with a computer and a USB cable, or type it in by hand.
Related programs
- Polynomial roots and stability
- Second-order step response metrics
- Discrete PID step response
- 1-DOF forced vibration
- RC circuit charging transient
All TI-84 Plus CE engineering programs · All TI-84 Plus CE programs