y(x): the function to plot. Use JS syntax, assuming x is pre-defined. For
example, Math.sin(Math.PI * x) will plot a sinusoid.

Num points: how many points to plot; the points are generated with linear
spacing in the given (inclusive) range. The plot will use linear interpolation
between points, so plots with a small number of points will be jagged approximations.
For more powerful interpolation, check the Interpolate box.

Show points: show the sampled points with small circles.

Start X: value of x to start the plot from.

End X: value of x to end the plot at.

Interpolate: if checked, performs cubic spline interpolation
between the sampled points (instead of the default linear interpolation).
The text box specifies how many points to generate using interpolation.
This number must be larger than Num points.