使用Mathematica绘制随机多项式的根
使用ListPlot和NSolve直接绘制:
(*返回系数为r和s之间整数的n次随机多项式*)
eq[n_, r_, s_] := RandomInteger[{r, s}, {n}] . Array[Power[x, # - 1] &, n]
(*返回给定随机多项式的根所对应的笛卡尔坐标*)
sol[n_, r_, s_] := {Re[#], Im[#]} & /@ (x /. NSolve[eq[n, r, s] == 0, x]) ListPlot[sol[400, 1, 6], PlotRange -> {{-1.5, 1.5}, {-1.5, 1.5}}, AspectRatio -> Automatic, PlotStyle -> {PointSize[Medium], Opacity[0.2], Black}]
使用Image和Fourier:
SetSystemOptions["SparseArrayOptions" -> {"TreatRepeatedEntries" -> 1}];
\[Gamma] = 0.12;
\[Beta] = 1.0;
fLor = Compile[{{x, _Integer}, {y, _Integer}}, (\[Gamma]/(\[Gamma] + x^2 + y^2))^\[Beta], RuntimeAttributes -> {Listable}(*,CompilationTarget->"C"*)];
<< Developer`
$PlotComplexPoints[list_, magnification_, paddingX_, paddingY_, brightness_] := Module[{RePos = paddingX + 1 + Round[magnification (# - Min[#])] &[Re[list]], ImPos = paddingY + 1 + Round[magnification (# - Min[#])] &[Im[list]],sparse, lor, dimX, dimY}, dimX = paddingX + Max[RePos];dimY = paddingY + Max[ImPos];Image[(brightness Sqrt[dimX dimY] Abs[InverseFourier[Fourier[SparseArray[Thread[{ImPos, RePos}\[Transpose] -> ConstantArray[1, Length[list]]], {dimY, dimX}]] Fourier[RotateRight[fLor[#[[All, All, 1]], #[[All, All, 2]]] &@Outer[List, Range[-Floor[dimY/2], Floor[(dimY - 1)/2]], Range[-Floor[dimX/2], Floor[(dimX - 1)/2]]], {Floor[dimY/2], Floor[dimX/2]}]]]])\[TensorProduct]ToPackedArray[{1.0, 0.3, 0.1}], Magnification -> 1]]
直接绘制10000个随机的复平面点图:
$PlotComplexPoints[ RandomComplex[{-1 - I, 1 + I}, 10000], 300, 20, 20, 10]
随机的150阶多项式的根的分布图:
expr = Evaluate@Sum[RandomInteger[{1, 10}] #^k, {k, 150}] &;
list = Table[N@Root[expr, k], {k, 150}];
$PlotComplexPoints[list, 320, 20, 20, 140]