This tool is designed to accompany a textbook on Differential Equations. The applet is simple but informative. The simplistic interface allows the user to input two functions f(x,y) and g(x,y), then after one click, the vector field of the phase plane associated with a system of differential equations of the form dx/dt=f(x,y), dy/dt=g(x,y) is sketched. A simple click with a mouse on the generated vector field produces a graph of the flow line. This applet provides a simple and effective illustration of a phase plane. The graphical display is very clear and looks like a standard DE textbook illustration. Window settings for the graph can be entered independently.
The direction field solver solves trigonometric, logarithmic and exponential functions.
The phase plane plotter has the option of enabling the x & y interval (min & max), the number of arrows, length of the arrow and a check box to display variable length arrows.
The site containing the applet would benefit from some introductory text (outside of the help window) on vector fields or, at least, a link to the corresponding material on the Web.
Introductory note on the objective of the applet and a brief theory or link should be there.
Phase portrait not displayed.
WolframAlpha Widget offers a better interactive interface and a sharable link for classroom discussion, assignments, homework etc. https://www.wolframalpha.com/widgets/