VectorPlot(func, xrange, yrange,[parameters], ...)
VectorPlot((sin(x),cos(y)), (x,-3,3), (y,-3,3))
VectorPlot((x,y), (x,-3,3), (y,-3,3), color="blue")+VectorPlot((y,-x), (x,-3,3), (y,-3,3), color="red")
