FlowCE

Calculus on your TI-84 Plus CE.
Type math the way it looks. Get answers the way your textbook writes them, and every step to get there.

FlowCE: exact answers, and every step to get there	KhiCAS + Flow: KhiCAS as Bernard Parisse made it, in FlowCE's look

Two apps for the TI-84 Plus CE, from one codebase:

• FlowCE is a computer algebra system built for Calc 1 and Calc 2. It gives exact answers (π²/6, not 1.64493), the decimal value right under them, and after an answer enter shows how to get it, step by step, the way a worked example in your textbook does.
• KhiCAS + Flow is Bernard Parisse's KhiCAS as he arranged it: his menus, keys and catalog, the 2D editor with the line as typed under it, the spreadsheet, programs and their debugger, drawn in FlowCE's look and at its speed. For KhiCAS users and for writing programs.

Install from the FlowCE page: plug in the calculator, pick one, click Install, and follow the short calculator prompts.

What's new

• 2.4: logs with any base: math, 0 (or log, the number, a comma, the base) draws log₂(8) as textbooks write it, with exact answers (log₄ 8 is 3/2) and steps for log equations; algebra's steps show for problems typed with ^ or x² (they did not); the TI-83 Premium CE's trig key offers all six functions.
• 2.3: the normal line and the osculating circle on the graph screen, the TI-83 Premium CE's own keys (trig, résol, frac), a start screen that flows into the app, and the installer's leftover files deleted at the first start (256 KB of archive back).
• KhiCAS + Flow 1.2: the graph shows the slope m and the radius R (X,T,θ,n: the full equation), the Config in khicasce's order, the TI-83 Premium CE's trig key offers sin, cos, tan and their inverses, faster menus.
• KhiCAS + Flow 1.1: KhiCAS's 1D command line in color (mode → 2D history off), the normal line and the osculating circle, the TI-83 Premium CE's keys.
• KhiCAS + Flow 1.0 replaces FlowCE Python: Bernard Parisse's KhiCAS as he arranged it (his menus, keys, catalog, 2D editor, spreadsheet, programs and debugger), in FlowCE's look and at its speed.
• 2.2: themes you can tell apart on the calculator's screen, their colors picked on a TI-84 Plus CE (2.2.1: a clean start screen).
• 2.1: faster: menus open in about half the time, everyday problems answer 25 to 45% sooner.
• 2.0: steps for algebra, Calculus → Applications, a real graph screen, nine themes, and more.

Which one?

	FlowCE	KhiCAS + Flow
Step-by-step solutions	calculus (derivatives, integrals, limits, sums, Taylor series) and algebra (equations, factoring, systems, inequalities)
Graphs	the graph screen: key points, pan and zoom, conics, parametric, polar, slope fields	the graph screen; small graphs kept in the history
Calculus → Applications	area, volumes, arc length, surface area, average value
Statistics and probability	data, box plots, regressions, distributions, tests	KhiCAS's spreadsheet and statistics
Menus and keys	FlowCE's	KhiCAS's, as Bernard Parisse arranged them (mode → Shortcuts lists them)
Programs (the program editor, the debugger)		yes, in Xcas syntax
Themes	nine	Paper
Download	FlowCE.b84	KhiCAS-Flow.b84

FlowCE is the one for class. KhiCAS + Flow is Bernard Parisse's KhiCAS as he made it, drawn in FlowCE's look and at its speed: for KhiCAS users and for programs. It replaces FlowCE Python. Install one at a time.

FlowCE

After an answer, press enter. Each step says what it does and the rule it uses (integration by parts, the chain rule, L'Hôpital's rule, the quadratic formula, elimination...); a part worked out on the side gets its own steps. ▲ and ▼ move from step to step, and F4 shows another method when there is one.

integration by parts	a quadratic, by the formula	a limit, L'Hôpital's rule

More steps

a system, by elimination	a log equation	an inequality
a sum, partial fractions	an absolute value	a derivative

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

Nine themes	Calculus → Applications	The graph screen

What 2.0 added

• Steps for algebra too. On top of derivatives, integrals, limits, sums and Taylor series: linear and quadratic equations, factoring, rational and radical equations, systems, exponential, log and trig equations, inequalities, absolute values and polynomial division.
• Applications of calculus, filled in like a worksheet. Area between curves, volumes by washers or shells, arc length, surface area and average value each open a short form (between y =, and y =, from x =, to x =). Leave the bounds empty and FlowCE finds where the curves meet; then enter shows the whole setup and the integral, step by step.
• A real graph screen. Arrows pan and + − zoom; trace along the curve; the key points (zeros, extrema, inflections) marked and labeled, exact when you jump to one; a table; tangent and normal lines and the osculating circle, areas, max and min on an interval. Equations in x and y (circles, ellipses), parametric and polar curves, slope fields.
• Nine themes. Paper, Night, Sand, Mint, Arctic, Ember, Rose, Grape and Forest. more → Themes shows each one on the whole screen as you move to it.
• analyze(f): domain, intercepts, asymptotes, increasing and decreasing, extrema, concavity and inflection points on one page.
• Statistics and probability in the more menu: enter data, box plots, fitted curves with r²; normal, t, chi-square, binomial and Poisson distributions, inverses, intervals and tests.
• What next? Under an answer, ▶ offers the likely next step: factor it, solve it for 0, graph it, take its derivative.
• Answers that read better. Matrices drawn as matrices, long lists of solutions wrapped, F4 with long division and the completed square, an antiderivative's derivative as a check, y′ in the symbols menu for y″ + 4y = 0 and f′(2).

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). Keys typed while a menu opens are kept, however fast you type.
• History and search. ▲ walks through your past calculations; enter reuses an input or an answer. ▼ searches every command, with descriptions and examples.
• 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, along with every menu and screen. A long calculation shows Calculating, and ON stops it; one that runs out of memory stops with a message instead of closing the app.

Applications, graphs, statistics

Calculus → Applications: a form	find where they meet, then the area	a volume, by washers
the graph screen: key points	equations in x and y	a slope field
analyze(f)	statistics: a fitted line	probability: the normal curve
▶: what to do next	a box plot	a t test

Themes

more → Themes opens a grid of all nine, each tile in its own colors. Moving to a tile shows that theme on the whole screen at once; enter keeps it, clear goes back. Paper and Night are FlowCE's light and dark looks; the others take after well-loved palettes (Solarized, Nord, Gruvbox, Rosé Pine, Dracula).

More screens

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 polar curve
history	command search	the calculus menu

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 an answer	its steps (calculus, equations, inequalities, factoring, divisions)
▶ after an answer	the row of next steps: ◀ ▶ move, enter does it
F4 on the steps page	another method, when there is one (long or synthetic division)
math	templates: fraction, root, integrals, derivative, limit, sum; 0: log with any base
▲ / ▼	history / search every command
F4 on an answer	its other forms (on an antiderivative, its derivative as a check)
(-)	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
calculus menu, 0	Applications: area, volumes, arc length, surface area, average value (FlowCE 2.0)
more → Graph	graphs the line or the answer (FlowCE 2.0: arrows pan, + − zoom, F1 trace, F2 zoom menu, F3 key points and tools, F4 table)
more → Themes	nine themes, shown as you move (FlowCE 2.0)
more → Statistics, Probability	data and fitted curves, distributions and tests (FlowCE 2.0)
mode	settings (Simplify answers on or off), shortcuts, about
2nd quit	quit (your session is kept)

KhiCAS + Flow

KhiCAS's screens, drawn in FlowCE's look: its F-key menus rise from the key as numbered lists, the 2D editor is a panel at the bottom with the line as typed under it (the caret and a selection in both), the history reads like KhiCAS's, and the catalog, the spreadsheet, the periodic table and the program debugger keep KhiCAS's keys. mode → Shortcuts lists them; mode → Arrows by character makes left and right step through the typed line instead of the 2D; mode → 2D history off gives KhiCAS's command line, the input and the history as text in KhiCAS's colors.

the 2D editor, the line as typed under it	KhiCAS's menus, from the F-keys
the spreadsheet (stat)	the periodic table

Install

The FlowCE page selects the installer for your OS. Open it in Chrome or Edge with the calculator plugged in, pick FlowCE or KhiCAS + Flow, 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).

OS 5.8.5: the page selects arTIfiCE v3 and guides you through Inequalz, AsmHook2, then INST. The page supplies and transfers all required files; there is nothing to download or select yourself. It prepares RAM and starts INST automatically, with two short calculator prompts in between. TI Connect CE instructions are also available. OS 5.8.4.0058 still uses v2.1. The one-enter automatic finish above applies to the v2.1 path. Keep your current OS; upgrading is not necessary to use FlowCE.

You need a TI-84 Plus CE (or TI-83 Premium CE). 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

OS 5.3–5.8.4 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 KhiCAS-Flow.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 (KhiCAS + Flow: KhiFlow).

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.

Building

FlowCE 2.3 builds with the CE C/C++ toolchain's nightly release (2.2.4 and earlier: v15) plus g++ and python3. Clone with --recursive (the engine is the src/giac submodule). tools/dev/build.sh en-steps-v15-nightly builds it in WSL from the working tree (APPLANG=en STEPS=1; tools/dev/wsl_build_v15.sh links the app and cuts it into the AppIns appvars installed by the INST program). KhiCAS + Flow builds with tools/dev/build.sh en-khicas-v15-nightly (APPLANG=en KHICAS=1). FlowCE Python 1.9.1 is the v1.9.1-rc1 tag, built with CEdev v14.2 and ./mkappen. tools/emu/ drives the CEmu emulator for the regression tests, the 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, by Tommy Bell, 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.

Parts of FlowCE 2.0 (the algebra steps, the graph screen, analyze, statistics and probability) were adapted from DeltaCE, a GPL-3.0 fork of FlowCE.