Graphing calculator

How to use it

1. Type f(x). Multiplication can be written 2x, 2*x or 2 × x; functions need brackets, as in sin(x).
2. Optionally type g(x) to compare two curves.
3. Set the left and right ends of the x range. The plot shows the x range at the bottom and the y range at the right.

How it works

The text is parsed into an expression tree (no code is executed) and evaluated at many x values. The plot is drawn from those values, with the axes through 0 when they fall inside the window. Crossings are the zeros of f − g.

Worked example

f(x) = x² − 2 on −4 to 4, with g(x) = x. The zeros of f are x = ±√2 ≈ ±1.414214 and f(0) = −2. The curves meet where x² − 2 = x, that is x = −1 and x = 2, so the crossings are (−1, −1) and (2, 2).

Tips

• Zoom by changing the x range: a tighter window shows more detail and gives better extremes.
• Use abs(x) for the absolute value and sqrt(x) for square roots; x^(1/3) is not defined for negative x here.
• Angles are in radians: sin(pi/2) = 1.