Function Graph Plotter

📖 About This Tool

The quickest way to understand a function is to look at it. Textbook figures are frozen: change one coefficient and you have to redraw by hand. Here you edit a digit in the expression and the curve moves at once, so the effect of a parameter stops being something you have to imagine. What happens as a grows, which way a constant term shifts the curve, why the graph breaks where a denominator hits zero: seeing it beats hearing it explained ten times.

Several curves can share one canvas, each with its own colour, which makes comparison easy. Put y=x, y=x squared and y=x cubed together and their growth rates are obvious; nudge a coefficient and watch where two lines cross, with the intersection coordinates printed on the plot. Expressions accept arithmetic, parentheses, powers, trigonometric, logarithmic, exponential and absolute value functions in familiar notation, such as sin(x)+x/3, 2^x, log(x) or abs(x).

Axis ranges, grid density and tick labels are all adjustable. Where a function is undefined, such as 1/x at x=0, the curve is broken rather than joined by an ugly vertical line, a detail that many simple plotters get wrong. Intercepts with the axes and local extrema are marked, and hovering over a curve reads off the function value at that abscissa.

Export PNG to drop into homework or handouts, or SVG for further editing in layout software. Every computation runs locally in the browser: nothing is sent over the network and nothing you type is stored.

Each curve is evaluated at a fixed number of points across the visible domain, and consecutive points are joined only when both are finite and the interval between them did not cross a pole. That is how 1/x breaks cleanly at zero instead of drawing a vertical streak through the origin. Raising the sample count smooths sharp turns near an asymptote, at the cost of a slower redraw.

✨ Features

• Multiple curves: up to six, each with its own colour and line style.
• Expression parsing: arithmetic, powers, trigonometry, logarithms, exponentials, absolute value and nested parentheses.
• Automatic breaks: undefined points split the curve instead of drawing a false vertical line.
• Key point marking: intercepts and extrema labelled, hover to read values.
• Adjustable axes: ranges, grid density and tick display are all configurable.
• Export PNG and SVG: bitmap for insertion, vector for further editing.

🚀 How to Use

1. Type a function in the expression field, such as sin(x)+x/3, using x as the variable.
2. To compare, add a curve and enter a second expression with its own colour.
3. Set the horizontal and vertical ranges plus grid density.
4. Press plot: the graph appears on the right with key points marked.
5. Export PNG or SVG when the figure looks right.

⚠️ Notes

• Variable name: the independent variable is always x; any other letter is treated as a constant and will error.
• Trigonometric units: radians by default; multiply degree values by pi/180 yourself if needed.
• Domain limits: logarithms are plotted only where the argument is positive.
• Sampling: more samples mean a smoother curve but slower drawing; the default balances both.
• Study aid only: the figure comes from numeric sampling and is no substitute for a proof.