How to Use
Enter the functions f (x,y) and g (x,y) in the text input fields marked "f(x,y)=" and "g(x,y)=".

 Example: f (x,y)=-y, g (x,y)=x

Compute and enter the divergence and curl into the corresponding text input fields: field marked "div F=" for divergence, field marked "curl F=" for curl.

 Example: for F (x,y)=<-y,x>, div F=0 and curl F=2

Click the "Graph" button (this button also refreshes the graph).

Choose the initial point (x,y).

 Example: (x,y)=(1,0)

This can be done either of two ways:

To erase the graph and all input fields, click the "Clear" button.
 Positive divergence: F (x,y)=<x,y>

 Positive curl: F (x,y)=<-y,x>

Other Notes
The starting square and the resulting quadrilateral (both drawn in blue) give the basis for the geometric interpretations of divergence and curl: The flow curve segments are graphed by determining numerical approximations using the classical (order four) Runge-Kutta Method.