Graphing Calculator

Type a function, see the curve

Type x^2 and a parabola appears. Swap it for sin(x) and you get the familiar wave rolling across the x-axis. The graph redraws as you type, so there’s no Plot button to hunt for, no page reload, no waiting.

You’re looking at a live coordinate plane. The vertical line is the y-axis, the horizontal one is the x-axis, and the faint gridlines carry numeric labels so you can read values straight off the plot. Drag anywhere on the canvas to slide the view around. Spin the mouse wheel to zoom toward your cursor. Lost? One click on Reset view snaps you back to the standard window, roughly x and y from -10 to 10.

What you can plot

Every function is written in terms of x. A few that show off the range:

• x^2 draws a parabola; x^3 gives you the classic S-shaped cubic
• 1/x produces a hyperbola with a clean break at x = 0 (the curve never crosses the y-axis, and the plotter knows not to draw a fake vertical line through the gap)
• sqrt(x) only exists for x greater than or equal to 0, so the left half of the plane stays empty
• 2*x+3 is a straight line with slope 2 and a y-intercept at 3
• sin(x), cos(x), and tan(x) handle trig, with tan showing its periodic asymptotes correctly

You can mix operators and functions freely: cos(x)*x, abs(sin(x)), floor(x). Beyond the basics, the parser knows sqrt, abs, log (natural log), log10, exp, floor, ceil, and round, plus the constants pi and e. So sin(pi*x) and e^x both work.

Overlaying several functions

Click Add function to drop in a second, third, or fourth curve, each in its own color. This is where comparisons get easy. Plot sin(x) against cos(x) and the quarter-period phase shift is obvious. Stack x, x^2, and x^3 together to watch how fast higher powers pull away from the line near the edges. Remove any row with the ✕ button when it’s done its job.

How the math gets evaluated

Here’s the part most online graphers get wrong. A lot of them feed your typed text straight into JavaScript’s eval(), which is both a security hole and a way to produce weird results. This one parses the expression itself.

The string gets broken into tokens (numbers, operators, the variable, function names), reordered into Reverse Polish Notation with the shunting-yard algorithm so precedence is respected, then evaluated once per pixel column as it sweeps across the screen. Exponents bind tighter than multiplication, multiplication tighter than addition, parentheses override everything, exactly the order you learned in algebra. If you type something it can’t make sense of, it tells you it couldn’t parse it instead of crashing or silently drawing nonsense.

Questions people ask

Why does my graph have gaps or missing pieces?

That’s usually correct behavior. sqrt(x) has no real value for negative x, and 1/x is undefined at zero, so the plotter lifts its pen rather than inventing points. It also skips the near-vertical jump across an asymptote, which is why tan(x) looks clean instead of streaked.

Can I use degrees instead of radians?

Trig functions work in radians, same as standard math libraries. To feed degrees, convert inside the expression: sin(x*pi/180) treats x as degrees.

How do I write multiplication and powers?

Use * for multiply and ^ for powers. So three x squared is 3*x^2. Implicit multiplication like 3x and 2(x+1) is accepted too, but the explicit form is harder to get wrong.

Does anything I type get sent anywhere?

Nope. The parser and the canvas both run in your browser. Your functions never leave the page, and there’s nothing to log in to.

What’s the largest expression I can plot?

There’s no hard cap. You can nest functions and parentheses as deep as you like, for example sin(cos(x)+1/(x^2+1)), and it’ll evaluate fine as long as the syntax is valid.

Can I plot vertical lines like x = 4?

Not directly, since every function is solved for y from a given x. A near-vertical line is the closest you’ll get, something like 1000*(x-4) rises almost straight up around x = 4.