Overview

Efunction is a lightweight mathematical graphing tool developed by Data Network Technology Lab. Type an expression and its graph appears on the canvas instantly — no type switching and no mandatory sign-up. All rendering and computation run on your own device, and an account is optional: sign in only when you want to back your schemes up to the cloud.

Key Features

Instant Plotting Engine

Supports sin, cos, tan, sqrt, abs, log, ln, exp and more, rendered in real time on Canvas. Efunction recognises what you typed — explicit function, implicit equation, inequality, differential equation or a custom function definition — without asking you to choose a type first.

Implicit Curves & Inequality Shading

Any equation in x and y is plotted directly, e.g. x^2+y^2=1, x^2/4+y^2/9=1 or the heart curve x^3+y^3-3x*y=0. Inequalities such as y>x^2 and x^2+y^2<1 shade the region in the curve colour at 20% opacity.

Differential Equations

y'=x-y draws a slope field together with the solution curve through the initial value. Second-order equations are supported too: y''=-0.2y'-y, 0, 1, 0 is solved with RK4 and drawn as a solution curve only.

Parametric & Polar Curves

Comma-separated x(t) and y(t) give a parametric curve; an expression in theta such as 2cos(3theta) gives a polar curve. Both support ranges and multi-condition domains.

Infinite Zoom & Pan

Wheel, drag, pinch and double-click all zoom around the pointer. Zoom carries no product-level limits — like Desmos and GeoGebra it goes down to the limit of double precision, with axis labels switching to scientific notation automatically.

Exact Intersections

Every curve type can be intersected with any other — explicit, implicit, inequality boundary, polar, parametric and differential equations. Results prefer exact forms such as π or radicals over decimals, and clicking a result jumps the view to that point.

Derivatives & Tangents

Right-click or long-press a curve to generate its derivative or the tangent line at that point; both are added to the scheme as new curves. Hovering an integral curve also shows the area of that interval.

Parameter Sliders

Write k=3/4 or k=2x+1 to create a parameter — a parameter is a function. Drag the slider and every dependent curve updates live, and values are kept as exact expressions instead of being flattened into decimals.

Storage, Export & Themes

Schemes are stored in your browser by default, and you can export them as a JSON backup file at any time. Signing in is optional — it lets you back up selected schemes to the DNT cloud and restore them on another device. Nothing is uploaded unless you choose cloud backup. Also exports the canvas as a 2× resolution PNG, with light and dark themes and instant switching between English, Traditional Chinese and Simplified Chinese.

Why Efunction?

Rendering, parsing and computation all happen on your own device — expressions are parsed with Math.js, math input is typeset with MathLive, and exact intersection values are recovered by the nerdamer symbolic engine. Schemes are stored locally by default, and an optional account lets you back them up to the DNT cloud for use across devices. Nothing leaves your device unless you choose to upload it.

Blazing Fast

Instant rendering with optimized canvas performance

Local-first & Private

Stays on your device by default; cloud backup is opt-in only

Works Offline

No internet connection needed for local use after first load

Responsive

Seamless experience on desktop, tablet, and mobile

Try These

Heart Curve

Type x^3+y^3-3x*y=0 — an implicit curve, graphed exactly as written.

Polar Rose

Type 2cos(3theta) — a three-petal rose, plotted straight from polar coordinates.

Damped Oscillator

Type y''=-0.2y'-y, 0, 1, 0 — a second-order differential equation solved live, smooth at any zoom level.

Lissajous Figure

Type cos(t), sin(2t) — a parametric curve in a single line.

Shaded Region

Type x^2+y^2<1 — an inequality, filled in the curve's own colour.

Area Under a Curve

Set two bounds to integrate, then hover the curve to read the area of that interval.

Define Your Own Functions

Define f(x)=x^2+1 once, then use it anywhere — y=f(x)+1 just works.

Live Parameters

Write k=3/4, then y=k*sin(k*x); drag the slider and the curve morphs in real time.

Supported Languages

English繁體中文（香港）简体中文

Contact

Learn more about Efunction or report issues at https://dnteam.top