Διανυσματικά πεδία

Clear["Global`*"]
F2D = {x - y, x*y};
StreamPlot[F2D, {x, -5, 5}, {y, -5, 5}, PlotLegends -> Automatic, 
 Background -> White]

StreamPlot[F2D, {x, -5, 5}, {y, -5, 5}, StreamColorFunction -> None, StreamPoints -> {{{{2, 1}, Red}, {{-1, 4}, Green}, Automatic}}]

3D

Clear["Global`*"]
F3D = {x - y, x*y, y/x};
VectorPlot3D[F3D, {x, -5, 5}, {y, -5, 5}, {z, -2, 6}, PlotLegends -> Automatic]