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A differential equation of the form $y^\prime = f(x,y)$ defines a slope field: an assignment to each point $(x,y)$ in the plane to a number $f(x,y)$ which specifies the slope of any solution curve to the differential equation passing through that point.
In this graphing calculator, you can enter such a function in the menu to the upper right, using standard mathematical function such as sin,cos,tan,e^,ln,… and operations like +-*/ ^. Your function may include the coordinates $x,y$, as well as a parameter $t$ (time, which controls animation), and the three parameters $a,b,c$ which can be manipulated using sliders in the menu.