FlowCE

Calculus on your TI-84 Plus CE.
Type math the way it looks. Get answers the way your textbook writes them, and now the steps.

FlowCE is a computer algebra system for the TI-84 Plus CE, built for Calc 1 and Calc 2. It gives exact answers: π²/6, not 1.64493; ln|sec x + tan x| + C; (2n²+3n+1)/(6n²). The decimal value sits right under the exact one. The interface is new from top to bottom: a clean light or dark look, math drawn as you type it, and keys that work the way a TI user expects.

Install it from the FlowCE page: plug in the calculator, pick a version, click Install, then press enter once on the calculator.

Two versions

	FlowCE	FlowCE Steps (beta)
Version	1.9, stable	2.0 beta 1
Step-by-step solutions		derivatives, integrals, limits, sums, Taylor series
Programs in Python syntax	yes	no (no room left for it)
Download	FlowCE.b84	FlowCE-steps.b84

Both have everything else below. They don't fit on the calculator together: install one.

Steps (beta)

After a derivative, an integral, a limit, a sum or a Taylor polynomial, press enter: FlowCE shows how to get the answer, the way a worked example in a textbook does. Each step says what it does and the rule it uses (integration by parts, the chain rule, L'Hôpital's rule, partial fractions, the ratio test...); a part worked out on the side, like the integral left after integrating by parts, gets its own steps. ▲ and ▼ move from step to step.

integration by parts	a limit, L'Hôpital's rule	a sum, partial fractions
a derivative, the product rule	a Taylor polynomial	enter after an answer

Not every problem has steps yet: when no textbook method explains the answer, it says so. It's a beta: if a step looks wrong, please open an issue with what you typed, or post on the Cemetech thread.

Highlights

• Type math as it looks. Fractions, powers, roots, integrals, sums, limits and derivatives are drawn in 2D while you type. / makes a fraction of what is before it, ^ opens an exponent, and the arrows move through the boxes in the order you read them. Commands from the menus and the search come with a box for each argument, labeled with what goes in it, and a line under the input says what the command does, with an example.
• Answers like your textbook. arctan((x+1)/2), x − x³/6 + x⁵/120 + O(x⁶), C1·cos(x) + C2·sin(x), polynomials in descending powers, log meaning base 10, + C on antiderivatives. Press F4 for other forms: simplified, one fraction, factored, expanded, decimal. To keep answers exactly as computed, turn off Simplify answers in mode.
• Calculus 1, 2 and 3. Derivatives, integrals (trig integrals, trig substitution, partial fractions, arc length and surface area), improper integrals that say diverges when they do, limits that say does not exist (with the left and right values), series and power series sums, Taylor series, Riemann sums, differential equations with initial values, parametric and polar areas, gradients, multiple integrals, complex numbers, vectors, matrices.
• Keys that work like a TI's. (-) is a minus sign and 2nd (-) is Ans. Starting a line with ×, ÷, +, − or ^ works on the last answer (× 2 enter doubles it). 2nd enter brings back your last input, and sto→ stores (5 → b).
• Graphs. Graph the line you typed, or the last answer, in one step. Trace along the curve, zoom, find roots and extrema, and see a table of values.
• History and search. ▲ walks through your past calculations; enter reuses an input or an answer. ▼ searches every command, with descriptions and examples.
• Paper and Night themes, switched from the more menu.
• Tested on the calculator itself. Before a release, about 900 Calc 1–3 problems run on an emulated TI-84 Plus CE and their answers are checked against a computer's. A long calculation shows Calculating, and ON stops it; one that runs out of memory stops with a message instead of closing the app.

Screenshots

an antiderivative, with + C	typing a definite integral	Σ 1/n² = π²/6
a power series: −ln(1−x)	a limit that does not exist	a Riemann sum, index i
∫ sec³x	a trig substitution	an initial value problem
F4: other forms	trace along a graph	a table of values
history	command search	Night theme

Install

The easy way: the FlowCE page. Open it in Chrome or Edge with the calculator plugged in, pick FlowCE or FlowCE Steps, and click Install: it checks the calculator, erases its archive (after you agree), sends FlowCE and opens the installer. Press enter once on the calculator: it installs and restarts by itself. On Windows it needs TI Connect CE 6.1 or newer installed (for its USB driver).

You need a TI-84 Plus CE (or TI-83 Premium CE) on OS 5.3 to 5.8.4. FlowCE fills most of the memory (about 2.8 MB), so installing it erases the calculator's apps and archived files: back up anything you want to keep first. FlowCE is a computer algebra system: follow your class and test rules (some tests, like the ACT, don't allow one).

By hand, with TI Connect CE:

1. Clear the memory: 2nd + (MEM) → 7:Reset... → right arrow twice to ALL → 1:All Memory... → 2:Reset.
2. Send the bundle: download FlowCE.b84 or FlowCE-steps.b84, drag it onto the calculator in TI Connect CE and send it.
3. Run the installer: prgm → enter → enter opens the arTIfiCE shell; enter starts INST and enter again installs. It counts down to 0; don't touch the calculator.
4. At "Success! Will now reset", press enter (a few times if the screen looks odd).
5. Start: clear, then apps → FlowCE.

1. Clear the memory	3. Run the installer	5. Start FlowCE

If something goes wrong

• The screen freezes at "Success! Will now reset": press the reset button on the back of the calculator (a pen tip or a paperclip). FlowCE stays installed.
• The calculator acts strangely (menus glitch, TI Connect CE stays on "refreshing"): clear the RAM: 2nd + (MEM) → 7:Reset... → 1:All RAM... → 2:Reset. This does not remove FlowCE.
• The calculator stays unresponsive: hold the reset button for a few seconds.

Keys

Key	What it does
F1 to F5	menus: algebra, calculus, trig, symbols, more (with 2nd or alpha: more menus)
F1 / F2 action after typing	applies to what you typed: x^2−1 then Factor is factor(x^2−1) (on an empty line: the last answer)
enter after a calculus answer	its steps (FlowCE Steps)
math	templates: fraction, root, integrals, derivative, limit, sum
▲ / ▼	history / search every command
F4 on an answer	its other forms
(-)	a minus sign; 2nd (-) is the last answer (Ans)
+ − × ÷ ^ x² first	works on the last answer, as on a TI (× 2 is Ans·2)
2nd enter	the last input again (ENTRY); press again for the one before
sto→	stores a value: 5 → b
clear	erases the line; on an empty line, the answer
ON or clear while computing	stops the calculation
more → Graph	graphs the line or the answer; in the graph: F2 window and curve study, 2nd graph table
mode	settings (Simplify answers on or off), shortcuts, about
2nd quit	quit (your session is kept)

Building

FlowCE builds with the CE C/C++ toolchain (CEdev v14.2) plus g++ and python3. Clone with --recursive (the engine is the src/giac submodule). ./mkappen builds the English app: AppIns appvars (.8xv) installed by the INST program, and FlowCE.b84 for TI Connect CE. After make clean, STEPS=1 ./mkappen builds FlowCE Steps (step-by-step solutions instead of Python syntax), and UNITS=1 ./mkappen builds physical units instead of Python syntax. The step-by-step code is on the dev/ux-speed branch; main is the 1.9 release. tools/dev/build.sh builds in WSL from the working tree, tools/emu/ drives the CEmu emulator for regression tests, screenshots and the GIFs above, and tests/host/ holds host tests of the editor and the 2D layout.

The app must fit in 43 flash pages (at most 2,818,045 bytes); the build prints the room left.

Credits and license

FlowCE is a fork of KhiCAS by Bernard Parisse.

• Math engine: Giac, by Bernard Parisse and contributors (Institut Fourier, Université Grenoble Alpes).
• Console interface: adapted from Eigenmath for the Casio Prizm by G. Maia, Mike Smith, Nemhardy and LePhenixNoir.
• Thanks to Adrien Bertrand, Xavier Andreani and the TI-83/84 development community, especially Jacob Young, commandblockguy and Matt Waltz.
• Installer: arTIfiCE by YvanTT.
• Fonts: Atkinson Hyperlegible (Braille Institute) and STIX Two, under the SIL Open Font License (tools/fonts/src).

FlowCE is free software under the GNU General Public License, version 3 or later. It comes with no warranty.