Formula Graph
Simply type the expression or formula to graph, and it will display a plot of the curve.
LEFTclick  zoom in 
RIGHTclick  zoom out 
drag mouse  pan graph 
hover over variable  shows curve family 
You can visualise equations of the form:
y = f(x)  plot y as a simple function of x 
x = f(t); y = f(t)  parametric function (e.g. x and y vary over time)  specify the bounds of parameter t 
r = f(t)  polar function, radius as a function of angle  specify range of angle t 
f(x,y) = 0  implicit function  plots contours of where f = 0 

Functions can have free parameters  use letters or words, and they will appear in the "variables" panel
 click on the value of a variable, and you can drag the slider around to show how the parameter changes the shape of the curve
 rightclick on a variable and choose "animate" to visualise a range of values of the parameter.

Multiple functions can be plotted using "equations... add/remove"

Sets of equations can be stored or loaded from the server using "equations... save/load"

Data can be fitted to functions with arbitrary parameters (least squares)
 type or paste a list of x and y coordinates into the "data" tab.
Should accept data from any application as long as X and Y are interleaved.
 use "data... draw points" to place data points by clicking on the graph 
these points can also be copied out to other applications

Functions can be selected from a library of interesting formulae  choose a category.