(************** Content-type: application/mathematica ************** CreatedBy='Mathematica 5.2' Mathematica-Compatible Notebook This notebook can be used with any Mathematica-compatible application, such as Mathematica, MathReader or Publicon. The data for the notebook starts with the line containing stars above. To get the notebook into a Mathematica-compatible application, do one of the following: * Save the data starting with the line of stars above into a file with a name ending in .nb, then open the file inside the application; * Copy the data starting with the line of stars above to the clipboard, then use the Paste menu command inside the application. Data for notebooks contains only printable 7-bit ASCII and can be sent directly in email or through ftp in text mode. Newlines can be CR, LF or CRLF (Unix, Macintosh or MS-DOS style). 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We want to force it to \ be a conical harmonic associated with opening half-angle \[Beta]. \ \>", "Text", FontColor->RGBColor[1, 0, 0]], Cell[BoxData[ \(P[\[Nu]_, \[Theta]_]\ = \ Hypergeometric2F1[\(-\[Nu]\), \[Nu] + 1, 1, \((Sin[\[Theta]/2])\)^2]\)], "Input"], Cell[TextData[{ "Let's consider a cone of opening half-angle \[Beta] = \[Pi]/6 \ (30\[Degree]). Our first goal is to estimate values ", Cell[BoxData[ \(TraditionalForm\`\[Nu]\_k\)]], " that put the 1st, 2nd, 3rd, ... zero of P at \[Beta] = \[Pi]/4." }], "Text", FontColor->RGBColor[1, 0, 0]], Cell[BoxData[ \(\[Beta] = \ \[Pi]/4\)], "Input"], Cell[BoxData[ \(Plot[P[\[Nu], \[Beta]], {\[Nu], 0, 20}, PlotStyle \[Rule] \ {Thickness[0.01], Hue[ .99]}, AxesLabel \[Rule] \ {\[Nu], "\<\>"}, TextStyle \[Rule] {FontSize \[Rule] 12}, PlotLabel\ \[Rule] \ "\"]\)], "Input"], Cell["\<\ From the graph, one sees that the approximate roots for this value of \[Beta] \ are at \[Nu]app = 2.5, 6.5, 10.5, 14.5, ..v (spacing is 4) . Now, let's \ obtain more precise values starting from \[Vee]app.\ \>", "Text", FontColor->RGBColor[1, 0, 0]], Cell[BoxData[ \(\[Nu]app\ = \ Table[\(-1.5\) + 4\ k, {k, 1, 7}]\)], "Input"], Cell[BoxData[ \(FindRoot[P[\[Nu], \[Beta]] \[Equal] 0, {\[Nu], \[Nu]app}]\)], "Input"], Cell[TextData[StyleBox["Assign these exact roots to rge array \[Nu]1 and \ check that P[\[Nu]1, \[Beta]] = 0", FontColor->RGBColor[1, 0, 0]]], "Text"], Cell[BoxData[ \(\[Nu]1\ \ = \ \[Nu] /. \ %\)], "Input"], Cell[BoxData[ \(P[\[Nu]1, \[Beta]]\)], "Input"], Cell[TextData[StyleBox["Plot the functions P[\[Nu]1[i], \[Theta]] from 0 to \ \[Beta]. The respective functions have a zero at \[Beta] and 0, 1, 2, 3, ... \ for \[Theta]<\[Beta].", FontColor->RGBColor[1, 0, 0]]], "Text"], Cell[BoxData[ \(\(\(\ \)\(Plot[{P[\[Nu]1[\([1]\)], \[Theta]], P[\[Nu]1[\([2]\)], \[Theta]], P[\[Nu]1[\([3]\)], \[Theta]], P[\[Nu]1[\([4]\)], \[Theta]], P[\[Nu]1[\([5]\)], \[Theta]], P[\[Nu]1[\([6]\)], \[Theta]], P[\[Nu]1[\([7]\)], \[Theta]]}, {\[Theta], 0, \[Beta]}, PlotStyle \[Rule] {{Hue[0], Thickness[0.008]}, {Hue[0.15], Thickness[0.008]}, {Hue[0.30], Thickness[0.008]}, {Hue[0.45], Thickness[0.008]}, {Hue[0.60], Thickness[0.008]}, {Hue[0.75], Thickness[0.008]}, {Hue[0.90], Thickness[0.008]}}, AxesLabel \[Rule] \ {\[Theta], "\<\>"}, TextStyle \[Rule] {FontSize \[Rule] 12}, PlotLabel\ \[Rule] \ "\"]\)\)\)], "Input"], Cell[TextData[StyleBox["Check the orthogonality of the the functions.", FontColor->RGBColor[1, 0, 0]]], "Text"], Cell[BoxData[ \(Table[ NIntegrate[ P[\[Nu]1[\([i]\)], \[Theta]]\ P[\[Nu]1[\([j]\)], \[Theta]]\ Sin[\ \[Theta]], {\[Theta], 0, \[Beta]}, AccuracyGoal \[Rule] \ 6], {i, 1, 7}, {j, 1, 7}] // TableForm\)], "Input"], Cell[TextData[StyleBox["Near the vertex of the cone \[Nu]0 = \[Nu]1[1] will \ dominate the series expansion for the potential", FontColor->RGBColor[1, 0, 0]]], "Text"], Cell[BoxData[ \(\[Nu]0\ = \ \[Nu]1[\([1]\)]\)], "Input"], Cell[BoxData[ \(\[CapitalPhi][r_, \[Theta]_]\ = \ r^\[Nu]0\ P[\[Nu]0, \[Theta]]\)], "Input"], Cell[BoxData[ \(E\[Theta]\ = \ \(-\ \((1/r)\)\)\ D[\[CapitalPhi][ r, \[Theta]], \[Theta]]\)], "Input"], Cell[BoxData[ \(\[Sigma][ r_]\ = \ \(-\ E\[Theta]\)\ /. \ \[Theta] \[Rule] \ \[Beta]\)], "Input"], Cell[BoxData[ \(Plot[Abs[\[Sigma][r]], {r, 0, 2}, PlotStyle \[Rule] {Hue[0.6], Thickness[0.008]}, AxesLabel\ \[Rule] \ {r, "\< \>"}, TextStyle \[Rule] \ {FontSize \[Rule] \ 14}, PlotLabel\ \[Rule] \ "\<|\[Sigma]| for a cone with \[Beta] = \ \[Pi]/4\>"\ ]\)], "Input"] }, Closed]], Cell[CellGroupData[{ Cell["Potential plot", "Subsection"], Cell[BoxData[ \(vv\ \ = \ Piecewise[{{\[CapitalPhi][ r, \[Theta]], \[Theta] < \[Beta]}, {0, \[Theta] > \ \[Beta]}}]\)], "Input"], Cell[BoxData[ \(v[x_, y_]\ = \ vv\ /. \ {r \[Rule] \ Sqrt[x^2 + y^2], \[Theta] \[Rule] \ ArcCos[y/Sqrt[x^2 + y^2]]}\)], "Input"], Cell[BoxData[ \(Plot3D[v[x, y], {x, 10^\(-6\), 1}, {y, 0, 1}, ViewPoint \[Rule] \ {1.2, 1.2, 1.2}, AspectRatio \[Rule] \ Automatic, AxesLabel \[Rule] {x, z, "\<\[CapitalPhi](x,z)\>"}, Ticks \[Rule] \ {Automatic, Automatic, {0, 0.5, 1}}, TextStyle \[Rule] {FontSize \[Rule] 12}]\)], "Input"], Cell[BoxData[ \(\(\(cp\ = \ ContourPlot[v[x, y], {x, 10^\(-6\), 3}, {y, 10^\(-6\), 3}, PlotPoints \[Rule] \ 50, ColorFunction \[Rule] Hue, ContourSmoothing \[Rule] \ True, \[IndentingNewLine]DisplayFunction \[Rule] \ Identity, AspectRatio \[Rule] \ Automatic]\)\(\[IndentingNewLine]\) \)\)], "Input"], Cell[BoxData[{ \(Needs["\"]\), "\[IndentingNewLine]", \(ce\ = \ PlotGradientField[\(-v[x, y]\), {x, 10^\(-6\), 3}, {y, 10^\(-6\), 3}, \[IndentingNewLine]ScaleFunction \[Rule] \ \((1 &)\), \ DisplayFunction \[Rule] \ Identity, AspectRatio \[Rule] \ Automatic]\)}], "Input"], Cell[BoxData[ \(Show[cp, ce, DisplayFunction \[Rule] \ $DisplayFunction]\)], "Input"] }, Closed]] }, Open ]] }, FrontEndVersion->"5.2 for Microsoft Windows", ScreenRectangle->{{0, 1024}, {0, 685}}, WindowSize->{1006, 652}, WindowMargins->{{-4, Automatic}, {2, Automatic}}, Magnification->1.5 ] (******************************************************************* Cached data follows. 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