Our Methodology

Every number on this site comes from a deterministic math engine written specifically for it. An expression you type is tokenized, parsed into an abstract syntax tree, and compiled into executable closures — it is never passed through eval or generated code. Roots are found with Brent’s method, derivatives with central differences, integrals with adaptive Simpson’s rule, and limits with two-sided numerical estimation.

Over 550 automated tests cover the expression engine, the numerical methods, graph state, the 3D plotter, and the scientific calculator. They run before every release, and a release does not ship unless all of them pass. When a computation cannot be performed reliably — a discontinuity, a non-converging integral, an out-of-domain evaluation — the tool reports the failure honestly instead of inventing a number.

The learn guides teach graphing from the ground up: what functions are, how domains and ranges work, how to read intercepts and asymptotes, and how to use each tool on this site. Every guide is written from standard mathematics curriculum material, not scraped or spun from other websites.

Before a guide is published, its mathematical claims are verified against the site’s own expression engine — the roots, example values, and domains stated in the text must match what the calculator itself computes. A human reviewer on the Graphing Calculator team then reads the guide for clarity and correctness. Each guide carries a “Last reviewed” date and a byline naming the reviewer, so you can see exactly when the check happened.

The built-in AI assistant can explain concepts, suggest expressions to plot, and help you set up graphs. It operates through a strict command schema: it may only issue calculator commands, and the calculator’s engine — not the AI — performs every computation. The assistant cannot change what the engine computes, and it cannot access your saved graphs.

Until the site owner configures an AI provider key, the assistant runs in a clearly labeled mock mode that says so on screen. It never pretends to be connected to a live model when it is not.

• No invented reviewers. We do not publish fake names, photos, or credentials. Review bylines say exactly who reviewed the content — the Graphing Calculator team — and when.
• No fabricated statistics. We do not claim user counts, ratings, or “best” rankings we cannot verify. Comparisons with other products state only publicly well-known facts.
• No copied interfaces. The calculator is an independent implementation. It does not reproduce any other product’s branding, interface, or copyrighted material.
• No hidden data collection. Graphs are stored in your browser; share links encode state in the URL. There are no accounts and no tracking analytics enabled by default. See the privacy policy for details.

If you find an error in a calculation or a guide, contact us with the details. Reported errors are investigated against the math engine, corrected when confirmed, and the guide’s “Last reviewed” date is updated to reflect the fix.