Graphics & Visualization

Show the Gradient Field on a Surface 

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X Plot3D[ (x^2 + y^2) Exp[1 - x^2 - y^2], {x, -3, 3}, {y, -3, 3}, PlotStyle -> Texture[StreamPlot[ Evaluate[-D[(x^2 + y^2) Exp[1 - x^2 - y^2], {{x, y}}]], {x, -3, 3}, {y, -3, 3}, Frame -> None, ImageSize -> Large]], Mesh -> None, ImageSize -> Large, PlotPoints -> 35]

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