Open channel: Manning, critical depth — a TI-84 Plus CE program

By E-Code · updated 2026-09-26

OPENCHAN is a TI-BASIC program for the TI-84 Plus CE. Trapezoidal channel: normal depth by bisection on Manning's equation, velocity, Froude number, critical depth, specific energy and the flow regime.

What it asks for and what it shows

It asks for 5 values at its prompts. In the example below it shows YN M, V M/S, FR, YC M, E SPEC, SUBCRITICAL.

Example run

One of its oracle test cases: “rectangular concrete, subcritical”. The inputs are typed in order, and the results are the values the case expects on the screen.

Step	Value
You enter
Input 1	12
Input 2	6
Input 3	0
Input 4	0.013
Input 5	0.0008
The screen shows
`YN M=`	1.074588014
`V M/S=`	1.861178399
`FR=`	0.573234742
`YC M=`	0.7415327354
`E SPEC=`	1.251141787
Text	SUBCRITICAL

How it's checked

4 test cases, each checked against an independent method. Replayed key by key on a virtual TI-84 Plus CE, they make 27 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 “Open channel: Manning, critical depth” (OPENCHAN).
Put it on your own calculator with a computer and a USB cable, or type it in by hand.

Related programs

All TI-84 Plus CE engineering programs · All TI-84 Plus CE programs