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Butterworthフィルタの極

Wolfram Language code: Manipulate[Module[{tf, poles}, tf = ButterworthFilterModel[n]; poles = Flatten@TransferFunctionPoles[tf]; Switch[view, "3Dビュー", Plot3D[Evaluate[Abs@tf[σ + I ω][[1, 1]]], {σ, -1.5, 0.5}, {ω, -1.5, 1.5}, PlotRange -> {0, n^2.6}, Mesh -> False, AxesLabel -> {σ, ω, None}, ImageSize -> 300], "2Dビュー", ComplexListPlot[poles, PlotStyle -> PointSize[Large], Epilog -> {Dashed, Pink, Circle[]}, PlotRange -> 1.1, ImageSize -> 300]]], {{n, 9, "次数"}, 1, 13, 1, Appearance -> "Labeled"}, {{view, "3Dビュー", ""}, {"2Dビュー", "3Dビュー"}}]