PhantoMath
A maths solver that explains every step — offline, free and open source.
Type a problem, get the answer as you type, then walk through the solution one step at a time:
what was done, why it is allowed, and what the rule looks like in general.
English · Русский
Why PhantoMath
- Steps you can actually follow. Each step is a short card: the formula before and after,
one sentence of explanation and, when you want it, a nested «More detail» screen down to
the arithmetic.
- «Why?» on every rule. Tap it to open a small theory article: the rule, its formula,
when it applies, a worked example and the typical mistake.
- Several ways to solve. A quadratic equation can be solved by factoring, by the formula,
by completing the square — switch between methods and compare.
- Answer as you type. No «Solve» button: the answer appears as soon as the input is complete.
- Works without internet. The solver runs on the phone. No account, no ads, no tracking,
no subscription — your homework never leaves the device.
- Two languages. The whole interface and every explanation in English and Russian.
- Open source. GPL-3.0. Read how a step is produced, fix it, add a topic.
What it solves
| Area | Examples |
|---|
| Arithmetic | order of operations, fractions, mixed numbers, percentages, column arithmetic, long division |
| Algebra | expand, factor, simplify, powers and roots, logarithms, partial fractions |
| Equations | linear, quadratic, biquadratic, rational, irrational, exponential, logarithmic, absolute value |
| Inequalities | linear, quadratic, rational, with absolute values, exponential and logarithmic |
| Systems | 2×2 and 3×3 linear systems: substitution, elimination, Cramer's rule, Gauss–Jordan, inverse matrix |
| Trigonometry | exact values, identities, trigonometric equations and inequalities, degrees ↔ radians |
| Functions | domain, range, intercepts, parity, extrema, inflection points, asymptotes, inverse function, graphs |
| Calculus | limits (incl. L'Hôpital), derivatives, indefinite / definite / improper integrals, area under a curve |
| Series | finite sums, arithmetic and geometric progressions, convergence tests, radius of convergence |
| Linear algebra | matrix operations, determinants, inverse, rank, matrix equations, vectors |
| More | complex numbers, combinatorics, conic sections, first- and second-order differential equations |
Install
PhantoMath is an Android app (Android 7.0+).
Build the APK yourself:
git clone https://github.com/diademoff/PhantoMath.git
cd PhantoMath
make apk
adb install -r app/build/app/outputs/flutter-apk/app-release.apk
You need Flutter 3.x, the Android SDK (platform 36), JDK 17+, Python 3.12 and
uv. make apk packs the Python solver together with SymPy into
the APK.
How it works
keyboard ─▶ formula tree ─▶ Python solver on the phone ─▶ steps + explanations ─▶ step screen
app/ — Flutter: a structural formula editor (slots, not text), the maths keyboard, the
step screen, graphs, notebook and settings.backend/ — mymath_backend, a Python solver on SymPy. One module
per topic produces the steps; every step names a template from a bilingual dictionary of
explanations.- On the phone the solver is embedded with
serious_python and answers on 127.0.0.1 — nothing
goes over the network.
Details: docs/ARCHITECTURE.md.
Development
cd backend && uv sync --python 3.12 --extra api # solver + HTTP layer for tests
make backend # solver as a FastAPI server on :8000
make run # the app on a connected device
make test # pytest + flutter test
make lint # ruff, mypy, flutter analyze
Over 1800 tests cover the solver and the app; a hand-written corpus pins the expected answer and
the order of steps for each topic, and tools/fuzz/ checks random problems against SymPy.
Contributions are welcome — see CONTRIBUTING.md.
License
GPL-3.0-or-later. You may use, study, share and change PhantoMath; derived works must
stay open under the same license.
