File:Chaotic Bunimovich stadium.png

English: billiards in a Bunimovich stadium, initial deviation is an angle of one degree

Mathematica source code

In[403]:= NN[v_]:=Sqrt[v[[1]]^2+v[[2]]^2]; Ang[v0_,va_,vb_]:=(va-v0).(vb-v0)/NN[va-v0]/NN[vb-v0]; 1st trajectory p0={0,0}; q0=\[Pi]/9; In[334]:= NSolve[(p0[[1]]+t Cos[q0]-1)^2+(p0[[2]]+t Sin[q0])^2==1,t] Out[334]= {{t\[Rule]0.},{t\[Rule]1.87939}} In[335]:= t0=1.8793852415718169`; p1=p0+t0{Cos[q0],Sin[q0]}; q1=-\[Pi]+(ArcCos[p1[[1]]-1]+q0); NSolve[p1[[2]]+t Sin[q1]\[Equal]-1,t] Out[338]= {{t\[Rule]1.89693}} In[180]:= t1=1.896927737347811; p2=p1+t1{Cos[q1],Sin[q1]}; q2=2\[Pi]-q1; NSolve[p2[[2]]+t Sin[q2]\[Equal]1,t] Out[183]= {{t\[Rule]2.3094}} In[202]:= t2=2.3094010767585043; p3=p2+t2{Cos[q2],Sin[q2]}; q3=2\[Pi]-q2; NSolve[(p3[[1]]+t Cos[q3]+1)^2+(p3[]+t Sin[q3])^2==1,t] Out[205]= {{t\[Rule]0.200212},{t\[Rule]2.19472}} In[405]:= t3=2.194718395858327; p4=p3+t3{Cos[q3],Sin[q3]}; Solve[Ang[p4,p3,{-1,0}]\[Equal]Ang[p4,({Cos[t],Sin[t]}+p4),{-1,0}],t] From In[405]:= \!\(\* RowBox[{\(Power::"infy"\), \(\(:\)\(\ \)\), "\<\"Infinite expression \ \\!\\(1\\/0\\^2\\) encountered. \\!\\(\\*ButtonBox[\\\"More\[Ellipsis]\\\", \ ButtonStyle->\\\"RefGuideLinkText\\\", ButtonFrame->None, \ ButtonData:>\\\"Power::infy\\\"]\\)\"\>"}]\) From In[405]:= \!\(\* RowBox[{\(Solve::"ifun"\), \(\(:\)\(\ \)\), "\<\"Inverse functions are \ being used by \\!\\(Solve\\), so some solutions may not be found; use Reduce \ for complete solution information. \ \\!\\(\\*ButtonBox[\\\"More\[Ellipsis]\\\", ButtonStyle->\\\"RefGuideLinkText\ \\\", ButtonFrame->None, ButtonData:>\\\"Solve::ifun\\\"]\\)\"\>"}]\) Out[407]= {{t\[Rule]1.0472},{t\[Rule]1.19548}} In[328]:= q4=1.1954752520981573; NSolve[p4[[2]]+t Sin[q4]\[Equal]1,t] Out[329]= {{t\[Rule]2.04289}} In[440]:= t4=2.0428873267106815`; p5=p4+t4{Cos[q4],Sin[q4]}; q5=2\[Pi]-q4; 2 nd trajectory In[384]:= P0={0,0}; Q0=\[Pi]/9+\[Pi]/180; In[386]:= NSolve[(P0[[1]]+t Cos[Q0]-1)^2+(P0[[2]]+t Sin[Q0])^2==1,t] Out[386]= {{t\[Rule]0.},{t\[Rule]1.86716}} In[387]:= T0=1.8671608529944035`; P1=P0+T0{Cos[Q0],Sin[Q0]}; Q1=-\[Pi]+(ArcCos[P1[[1]]-1]+Q0); NSolve[P1[[2]]+t Sin[Q1]\[Equal]-1,t] Out[390]= {{t\[Rule]1.87331}} In[391]:= T1=1.8733090735550966`; P2=P1+T1{Cos[Q1],Sin[Q1]}; Q2=2\[Pi]-Q1; NSolve[P2[[2]]+t Sin[Q2]\[Equal]1,t] Out[394]= {{t\[Rule]2.24465}} In[395]:= T2=2.2446524752687225`; P3=P2+T2{Cos[Q2],Sin[Q2]}; Q3=2\[Pi]-Q2; NSolve[(P3[[1]]+t Cos[Q3]+1)^2+(P3[]+t Sin[Q3])^2==1,t] Out[398]= {{t\[Rule]0.341712},{t\[Rule]2.23354}} In[419]:= T3=2.233539454680641`; P4=P3+T3{Cos[Q3],Sin[Q3]}; Solve[Ang[P4,P3,{-1,0}]\[Equal]Ang[P4,({Cos[t],Sin[t]}+P4),{-1,0}],t] From In[419]:= \!\(\* RowBox[{\(Power::"infy"\), \(\(:\)\(\ \)\), "\<\"Infinite expression \ \\!\\(1\\/0\\^2\\) encountered. \\!\\(\\*ButtonBox[\\\"More\[Ellipsis]\\\", \ ButtonStyle->\\\"RefGuideLinkText\\\", ButtonFrame->None, \ ButtonData:>\\\"Power::infy\\\"]\\)\"\>"}]\) From In[419]:= \!\(\* RowBox[{\(Solve::"ifun"\), \(\(:\)\(\ \)\), "\<\"Inverse functions are \ being used by \\!\\(Solve\\), so some solutions may not be found; use Reduce \ for complete solution information. \ \\!\\(\\*ButtonBox[\\\"More\[Ellipsis]\\\", ButtonStyle->\\\"RefGuideLinkText\ \\\", ButtonFrame->None, ButtonData:>\\\"Solve::ifun\\\"]\\)\"\>"}]\) Out[421]= {{t\[Rule]1.09956},{t\[Rule]1.76035}} In[423]:= Q4=1.786499618850784`; NSolve[(P4[[1]]+t Cos[Q4]+1)^2+(P4[]+t Sin[Q4])^2==1,t] Out[424]= \!\({{t \[Rule] \(-2.961831812996791`*^-16\)}, {t \[Rule] 1.874216860919306`}}\) In[428]:= T4=1.874216860919306`; P5=P4+T4{Cos[Q4],Sin[Q4]}; Solve[Ang[P5,P4,{-1,0}]\[Equal]Ang[P5,({Cos[t],Sin[t]}+P5),{-1,0}],t] From In[428]:= \!\(\* RowBox[{\(Power::"infy"\), \(\(:\)\(\ \)\), "\<\"Infinite expression \ \\!\\(1\\/0\\^2\\) encountered. \\!\\(\\*ButtonBox[\\\"More\[Ellipsis]\\\", \ ButtonStyle->\\\"RefGuideLinkText\\\", ButtonFrame->None, \ ButtonData:>\\\"Power::infy\\\"]\\)\"\>"}]\) From In[428]:= \!\(\* RowBox[{\(Solve::"ifun"\), \(\(:\)\(\ \)\), "\<\"Inverse functions are \ being used by \\!\\(Solve\\), so some solutions may not be found; use Reduce \ for complete solution information. \ \\!\\(\\*ButtonBox[\\\"More\[Ellipsis]\\\", ButtonStyle->\\\"RefGuideLinkText\ \\\", ButtonFrame->None, ButtonData:>\\\"Solve::ifun\\\"]\\)\"\>"}]\) Out[430]= {{t\[Rule]-1.35509},{t\[Rule]-0.642004}} In[432]:= Q5=-0.6420035368814776`; Illustration In[451]:= Show[Graphics[{ Thickness[.003], Line[{{-1,-1},{1,-1}}], Line[{{-1,1},{1,1}}], Circle[{1,0},1,{-\[Pi]/2,\[Pi]/2}], Circle[{-1,0},1,{\[Pi]/2,3\[Pi]/2}], RGBColor[254/256,194/256,0], Thickness[.0051],PointSize[.03], Line[{p0,p0+t0{Cos[q0],Sin[q0]}}], Line[{p1,p1+t1{Cos[q1],Sin[q1]}}], Line[{p2,p2+t2{Cos[q2],Sin[q2]}}], Line[{p3,p3+t3{Cos[q3],Sin[q3]}}], Line[{p4,p4+t4{Cos[q4],Sin[q4]}}], Line[{p5,p5+1.9{Cos[q5],Sin[q5]}}], Point[p5+1.9{Cos[q5],Sin[q5]}], RGBColor[188/256,30/256,71/256], Line[{P0,P0+T0{Cos[Q0],Sin[Q0]}}], Line[{P1,P1+T1{Cos[Q1],Sin[Q1]}}], Line[{P2,P2+T2{Cos[Q2],Sin[Q2]}}], Line[{P3,P3+T3{Cos[Q3],Sin[Q3]}}], Line[{P4,P4+T4{Cos[Q4],Sin[Q4]}}], Line[{P5,P5+1.9{Cos[Q5],Sin[Q5]}}], Point[P5+1.9{Cos[Q5],Sin[Q5]}] }],AspectRatio\[Rule]Automatic]