函数作图

Plot functions and inequalities

Graphing Calculator parses expressions with mathjs and renders them on a Mafs canvas. You can stack multiple functions, switch between equation and inequality, drag and zoom the view, and trace exact y values for any x. Everything runs in the browser.

1. Function list

• Expression field. Accepts standard math syntax: x^2, sin(x), sqrt(x), abs(x), exp(x). log means base-10 log; use ln for natural log.
• Operator. Click to cycle =, <, >, ≤, ≥. Equalities draw a curve, inequalities shade a region.
• Colour swatch. Click to cycle through the eight preset plot colours. Useful when comparing two similar curves.
• Eye icon. Hides a function from the graph and from trace results without removing the row.
• Trash icon. Removes the row entirely.
• Add Function. Appends a new empty row using the next colour in the rotation.

2. View, zoom, and pan

• Drag. Click and drag inside the graph to pan. The X and Y range inputs follow the new bounds.
• Wheel. Scroll to zoom around the cursor position. Zoom is clamped between range 1 and range 10000.
• X / Y range inputs. Type exact bounds when you need a specific window.
• ZStandard, ZTrig, ZDecimal, ZSquare. One-click presets equivalent to the TI-84 zoom shortcuts: −10..10, ±2π with ±4 vertical, ±1 close-up, and a 1:1 aspect adjustment.
• Reset. Restores the default −10..10 by −10..10 view.
• Grid, axes, numbers toggles. Show or hide the grid, the axis lines, and the tick labels independently.

3. Trace

• x input. Type a value and press Enter or click the crosshair button to evaluate every visible function at that x.
• Trace Results. Each entry stacks at the top of the list with the matched colour for each function. The stack keeps the last ten lookups; Clear empties it.