Noise in Eigenvalues plot Planned maintenance scheduled April 23, 2019 at 23:30 UTC (7:30pm...

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Noise in Eigenvalues plot



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4












$begingroup$


I am trying to Plot Eigenvalues of a Hamiltonian, but I am getting noisy plot, which is incorrect. Here is the code.



A1 = {{0, 1, 0, 0}, {1, 0, 0, 0}, {0, 0, 0, -1}, {0, 0, -1, 0}};
A2 = {{0, -I, 0, 0}, {I, 0, 0, 0}, {0, 0, 0, -I}, {0, 0, I, 0}};
A3 = {{0, 0, 0, -1}, {0, 0, 1, 0}, {0, 1, 0, 0}, {-1, 0, 0, 0}};
A4 = {{0, -I, 0, 0}, {I, 0, 0, 0}, {0, 0, 0, I}, {0, 0, -I, 0}};
A5 = {{1, 0, 0, 0}, {0, -1, 0, 0}, {0, 0, 1, 0}, {0, 0, 0, -1}};
A6 = {{0, 0, 0, -I}, {0, 0, I, 0}, {0, -I, 0, 0}, {I, 0, 0, 0}};
A7 = {{0, 0, 1, 0}, {0, 0, 0, 1}, {1, 0, 0, 0}, {0, 1, 0, 0}};
A8 = {{1, 0, 0, 0}, {0, 1, 0, 0}, {0, 0, -1, 0}, {0, 0, 0, -1}};
H[d_, λ_, β_, m_] :=
a (Sin[x] A1 + Sin[ky] A2) + A3 β +
d A4 + (t Cos[z] + 2 b (2 - Cos[x] - Cos[ky])) A5 + α*
Sin[ky] A6 + λ Sin[z] A7+m*A8;
ky = 0;
a = 1;
b = 1;
t = 1.5;
α = 0.3;
Plot3D[Eigenvalues[H[0.1, 0.5, 0.7, 0]][[4]], {x, -π, π}, {z, 0, 2 π}]


Mathematica graphics



Any help will be highly appreciated.










share|improve this question











$endgroup$

















    4












    $begingroup$


    I am trying to Plot Eigenvalues of a Hamiltonian, but I am getting noisy plot, which is incorrect. Here is the code.



    A1 = {{0, 1, 0, 0}, {1, 0, 0, 0}, {0, 0, 0, -1}, {0, 0, -1, 0}};
    A2 = {{0, -I, 0, 0}, {I, 0, 0, 0}, {0, 0, 0, -I}, {0, 0, I, 0}};
    A3 = {{0, 0, 0, -1}, {0, 0, 1, 0}, {0, 1, 0, 0}, {-1, 0, 0, 0}};
    A4 = {{0, -I, 0, 0}, {I, 0, 0, 0}, {0, 0, 0, I}, {0, 0, -I, 0}};
    A5 = {{1, 0, 0, 0}, {0, -1, 0, 0}, {0, 0, 1, 0}, {0, 0, 0, -1}};
    A6 = {{0, 0, 0, -I}, {0, 0, I, 0}, {0, -I, 0, 0}, {I, 0, 0, 0}};
    A7 = {{0, 0, 1, 0}, {0, 0, 0, 1}, {1, 0, 0, 0}, {0, 1, 0, 0}};
    A8 = {{1, 0, 0, 0}, {0, 1, 0, 0}, {0, 0, -1, 0}, {0, 0, 0, -1}};
    H[d_, λ_, β_, m_] :=
    a (Sin[x] A1 + Sin[ky] A2) + A3 β +
    d A4 + (t Cos[z] + 2 b (2 - Cos[x] - Cos[ky])) A5 + α*
    Sin[ky] A6 + λ Sin[z] A7+m*A8;
    ky = 0;
    a = 1;
    b = 1;
    t = 1.5;
    α = 0.3;
    Plot3D[Eigenvalues[H[0.1, 0.5, 0.7, 0]][[4]], {x, -π, π}, {z, 0, 2 π}]


    Mathematica graphics



    Any help will be highly appreciated.










    share|improve this question











    $endgroup$















      4












      4








      4





      $begingroup$


      I am trying to Plot Eigenvalues of a Hamiltonian, but I am getting noisy plot, which is incorrect. Here is the code.



      A1 = {{0, 1, 0, 0}, {1, 0, 0, 0}, {0, 0, 0, -1}, {0, 0, -1, 0}};
      A2 = {{0, -I, 0, 0}, {I, 0, 0, 0}, {0, 0, 0, -I}, {0, 0, I, 0}};
      A3 = {{0, 0, 0, -1}, {0, 0, 1, 0}, {0, 1, 0, 0}, {-1, 0, 0, 0}};
      A4 = {{0, -I, 0, 0}, {I, 0, 0, 0}, {0, 0, 0, I}, {0, 0, -I, 0}};
      A5 = {{1, 0, 0, 0}, {0, -1, 0, 0}, {0, 0, 1, 0}, {0, 0, 0, -1}};
      A6 = {{0, 0, 0, -I}, {0, 0, I, 0}, {0, -I, 0, 0}, {I, 0, 0, 0}};
      A7 = {{0, 0, 1, 0}, {0, 0, 0, 1}, {1, 0, 0, 0}, {0, 1, 0, 0}};
      A8 = {{1, 0, 0, 0}, {0, 1, 0, 0}, {0, 0, -1, 0}, {0, 0, 0, -1}};
      H[d_, λ_, β_, m_] :=
      a (Sin[x] A1 + Sin[ky] A2) + A3 β +
      d A4 + (t Cos[z] + 2 b (2 - Cos[x] - Cos[ky])) A5 + α*
      Sin[ky] A6 + λ Sin[z] A7+m*A8;
      ky = 0;
      a = 1;
      b = 1;
      t = 1.5;
      α = 0.3;
      Plot3D[Eigenvalues[H[0.1, 0.5, 0.7, 0]][[4]], {x, -π, π}, {z, 0, 2 π}]


      Mathematica graphics



      Any help will be highly appreciated.










      share|improve this question











      $endgroup$




      I am trying to Plot Eigenvalues of a Hamiltonian, but I am getting noisy plot, which is incorrect. Here is the code.



      A1 = {{0, 1, 0, 0}, {1, 0, 0, 0}, {0, 0, 0, -1}, {0, 0, -1, 0}};
      A2 = {{0, -I, 0, 0}, {I, 0, 0, 0}, {0, 0, 0, -I}, {0, 0, I, 0}};
      A3 = {{0, 0, 0, -1}, {0, 0, 1, 0}, {0, 1, 0, 0}, {-1, 0, 0, 0}};
      A4 = {{0, -I, 0, 0}, {I, 0, 0, 0}, {0, 0, 0, I}, {0, 0, -I, 0}};
      A5 = {{1, 0, 0, 0}, {0, -1, 0, 0}, {0, 0, 1, 0}, {0, 0, 0, -1}};
      A6 = {{0, 0, 0, -I}, {0, 0, I, 0}, {0, -I, 0, 0}, {I, 0, 0, 0}};
      A7 = {{0, 0, 1, 0}, {0, 0, 0, 1}, {1, 0, 0, 0}, {0, 1, 0, 0}};
      A8 = {{1, 0, 0, 0}, {0, 1, 0, 0}, {0, 0, -1, 0}, {0, 0, 0, -1}};
      H[d_, λ_, β_, m_] :=
      a (Sin[x] A1 + Sin[ky] A2) + A3 β +
      d A4 + (t Cos[z] + 2 b (2 - Cos[x] - Cos[ky])) A5 + α*
      Sin[ky] A6 + λ Sin[z] A7+m*A8;
      ky = 0;
      a = 1;
      b = 1;
      t = 1.5;
      α = 0.3;
      Plot3D[Eigenvalues[H[0.1, 0.5, 0.7, 0]][[4]], {x, -π, π}, {z, 0, 2 π}]


      Mathematica graphics



      Any help will be highly appreciated.







      plotting eigenvalues






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited 3 hours ago









      Michael E2

      151k12203483




      151k12203483










      asked 3 hours ago









      Hazoor ImranHazoor Imran

      313




      313






















          2 Answers
          2






          active

          oldest

          votes


















          3












          $begingroup$

          By default, the eigenvalues are ordered by absolute value. All the eigenvalues of this particular matrix have the same absolute value plus some rounding errors. Thus, it can easily happen, that the fourth eigenvalue is positive or negative, depending on the parameters.



          You can use Max to plot the largest eigenvalue:



          Plot3D[Max@Eigenvalues[H[0.1, 0.5, 0.7, 0.]], {x, -Pi, Pi}, {z, 0, 2 Pi}]


          enter image description here



          Alternatively, you may use the "Criteria" suboption of the Method "Arnoldi":



          Plot3D[
          Eigenvalues[
          H[0.1, 0.5, 0.7, 0], -1,
          Method -> {"Arnoldi", "Criteria" -> "RealPart"}
          ],
          {x, - Pi, Pi}, {z, 0, 2 Pi}]





          share|improve this answer









          $endgroup$













          • $begingroup$
            Thanks @ Henrik Schumacher
            $endgroup$
            – Hazoor Imran
            2 hours ago










          • $begingroup$
            You're welcome.
            $endgroup$
            – Henrik Schumacher
            2 hours ago



















          3












          $begingroup$

          Not sure why you pick the 4th element, but maybe this will help:



          ev4 = Eigenvalues[H[p, q, r, s]][[4]] /. 
          Thread[{p, q, r, s} -> {0.1, 0.5, 0.7, 0}];
          Plot3D[ev4, {x, -π, π}, {z, 0, 2 π}]


          enter image description here






          share|improve this answer









          $endgroup$













          • $begingroup$
            Thanks @ Michael E2, Is it possible to do this with an equation by the contourplot. Like ev4 = Eigenvalues[H[p, q, r, s]][[4]] /. Thread[{p, q, r, s} -> {0.1, 0.5, 0.7, 0}]; ContourPlot[ev4==-0.5, {x, -[Pi], [Pi]}, {z, 0, 2 [Pi]}]. In my case this is not working.
            $endgroup$
            – Hazoor Imran
            2 hours ago










          • $begingroup$
            @HazoorImran Yes, but set the value -0.5 on the right hand side to something bigger. For example ContourPlot[ev4 == 2, {x, -[Pi], [Pi]}, {z, 0, 2 [Pi]}].
            $endgroup$
            – Michael E2
            2 hours ago










          • $begingroup$
            Thanks @ Michael E2, Yes this work.
            $endgroup$
            – Hazoor Imran
            2 hours ago












          Your Answer








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          2 Answers
          2






          active

          oldest

          votes








          2 Answers
          2






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          3












          $begingroup$

          By default, the eigenvalues are ordered by absolute value. All the eigenvalues of this particular matrix have the same absolute value plus some rounding errors. Thus, it can easily happen, that the fourth eigenvalue is positive or negative, depending on the parameters.



          You can use Max to plot the largest eigenvalue:



          Plot3D[Max@Eigenvalues[H[0.1, 0.5, 0.7, 0.]], {x, -Pi, Pi}, {z, 0, 2 Pi}]


          enter image description here



          Alternatively, you may use the "Criteria" suboption of the Method "Arnoldi":



          Plot3D[
          Eigenvalues[
          H[0.1, 0.5, 0.7, 0], -1,
          Method -> {"Arnoldi", "Criteria" -> "RealPart"}
          ],
          {x, - Pi, Pi}, {z, 0, 2 Pi}]





          share|improve this answer









          $endgroup$













          • $begingroup$
            Thanks @ Henrik Schumacher
            $endgroup$
            – Hazoor Imran
            2 hours ago










          • $begingroup$
            You're welcome.
            $endgroup$
            – Henrik Schumacher
            2 hours ago
















          3












          $begingroup$

          By default, the eigenvalues are ordered by absolute value. All the eigenvalues of this particular matrix have the same absolute value plus some rounding errors. Thus, it can easily happen, that the fourth eigenvalue is positive or negative, depending on the parameters.



          You can use Max to plot the largest eigenvalue:



          Plot3D[Max@Eigenvalues[H[0.1, 0.5, 0.7, 0.]], {x, -Pi, Pi}, {z, 0, 2 Pi}]


          enter image description here



          Alternatively, you may use the "Criteria" suboption of the Method "Arnoldi":



          Plot3D[
          Eigenvalues[
          H[0.1, 0.5, 0.7, 0], -1,
          Method -> {"Arnoldi", "Criteria" -> "RealPart"}
          ],
          {x, - Pi, Pi}, {z, 0, 2 Pi}]





          share|improve this answer









          $endgroup$













          • $begingroup$
            Thanks @ Henrik Schumacher
            $endgroup$
            – Hazoor Imran
            2 hours ago










          • $begingroup$
            You're welcome.
            $endgroup$
            – Henrik Schumacher
            2 hours ago














          3












          3








          3





          $begingroup$

          By default, the eigenvalues are ordered by absolute value. All the eigenvalues of this particular matrix have the same absolute value plus some rounding errors. Thus, it can easily happen, that the fourth eigenvalue is positive or negative, depending on the parameters.



          You can use Max to plot the largest eigenvalue:



          Plot3D[Max@Eigenvalues[H[0.1, 0.5, 0.7, 0.]], {x, -Pi, Pi}, {z, 0, 2 Pi}]


          enter image description here



          Alternatively, you may use the "Criteria" suboption of the Method "Arnoldi":



          Plot3D[
          Eigenvalues[
          H[0.1, 0.5, 0.7, 0], -1,
          Method -> {"Arnoldi", "Criteria" -> "RealPart"}
          ],
          {x, - Pi, Pi}, {z, 0, 2 Pi}]





          share|improve this answer









          $endgroup$



          By default, the eigenvalues are ordered by absolute value. All the eigenvalues of this particular matrix have the same absolute value plus some rounding errors. Thus, it can easily happen, that the fourth eigenvalue is positive or negative, depending on the parameters.



          You can use Max to plot the largest eigenvalue:



          Plot3D[Max@Eigenvalues[H[0.1, 0.5, 0.7, 0.]], {x, -Pi, Pi}, {z, 0, 2 Pi}]


          enter image description here



          Alternatively, you may use the "Criteria" suboption of the Method "Arnoldi":



          Plot3D[
          Eigenvalues[
          H[0.1, 0.5, 0.7, 0], -1,
          Method -> {"Arnoldi", "Criteria" -> "RealPart"}
          ],
          {x, - Pi, Pi}, {z, 0, 2 Pi}]






          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered 3 hours ago









          Henrik SchumacherHenrik Schumacher

          60.7k585171




          60.7k585171












          • $begingroup$
            Thanks @ Henrik Schumacher
            $endgroup$
            – Hazoor Imran
            2 hours ago










          • $begingroup$
            You're welcome.
            $endgroup$
            – Henrik Schumacher
            2 hours ago


















          • $begingroup$
            Thanks @ Henrik Schumacher
            $endgroup$
            – Hazoor Imran
            2 hours ago










          • $begingroup$
            You're welcome.
            $endgroup$
            – Henrik Schumacher
            2 hours ago
















          $begingroup$
          Thanks @ Henrik Schumacher
          $endgroup$
          – Hazoor Imran
          2 hours ago




          $begingroup$
          Thanks @ Henrik Schumacher
          $endgroup$
          – Hazoor Imran
          2 hours ago












          $begingroup$
          You're welcome.
          $endgroup$
          – Henrik Schumacher
          2 hours ago




          $begingroup$
          You're welcome.
          $endgroup$
          – Henrik Schumacher
          2 hours ago











          3












          $begingroup$

          Not sure why you pick the 4th element, but maybe this will help:



          ev4 = Eigenvalues[H[p, q, r, s]][[4]] /. 
          Thread[{p, q, r, s} -> {0.1, 0.5, 0.7, 0}];
          Plot3D[ev4, {x, -π, π}, {z, 0, 2 π}]


          enter image description here






          share|improve this answer









          $endgroup$













          • $begingroup$
            Thanks @ Michael E2, Is it possible to do this with an equation by the contourplot. Like ev4 = Eigenvalues[H[p, q, r, s]][[4]] /. Thread[{p, q, r, s} -> {0.1, 0.5, 0.7, 0}]; ContourPlot[ev4==-0.5, {x, -[Pi], [Pi]}, {z, 0, 2 [Pi]}]. In my case this is not working.
            $endgroup$
            – Hazoor Imran
            2 hours ago










          • $begingroup$
            @HazoorImran Yes, but set the value -0.5 on the right hand side to something bigger. For example ContourPlot[ev4 == 2, {x, -[Pi], [Pi]}, {z, 0, 2 [Pi]}].
            $endgroup$
            – Michael E2
            2 hours ago










          • $begingroup$
            Thanks @ Michael E2, Yes this work.
            $endgroup$
            – Hazoor Imran
            2 hours ago
















          3












          $begingroup$

          Not sure why you pick the 4th element, but maybe this will help:



          ev4 = Eigenvalues[H[p, q, r, s]][[4]] /. 
          Thread[{p, q, r, s} -> {0.1, 0.5, 0.7, 0}];
          Plot3D[ev4, {x, -π, π}, {z, 0, 2 π}]


          enter image description here






          share|improve this answer









          $endgroup$













          • $begingroup$
            Thanks @ Michael E2, Is it possible to do this with an equation by the contourplot. Like ev4 = Eigenvalues[H[p, q, r, s]][[4]] /. Thread[{p, q, r, s} -> {0.1, 0.5, 0.7, 0}]; ContourPlot[ev4==-0.5, {x, -[Pi], [Pi]}, {z, 0, 2 [Pi]}]. In my case this is not working.
            $endgroup$
            – Hazoor Imran
            2 hours ago










          • $begingroup$
            @HazoorImran Yes, but set the value -0.5 on the right hand side to something bigger. For example ContourPlot[ev4 == 2, {x, -[Pi], [Pi]}, {z, 0, 2 [Pi]}].
            $endgroup$
            – Michael E2
            2 hours ago










          • $begingroup$
            Thanks @ Michael E2, Yes this work.
            $endgroup$
            – Hazoor Imran
            2 hours ago














          3












          3








          3





          $begingroup$

          Not sure why you pick the 4th element, but maybe this will help:



          ev4 = Eigenvalues[H[p, q, r, s]][[4]] /. 
          Thread[{p, q, r, s} -> {0.1, 0.5, 0.7, 0}];
          Plot3D[ev4, {x, -π, π}, {z, 0, 2 π}]


          enter image description here






          share|improve this answer









          $endgroup$



          Not sure why you pick the 4th element, but maybe this will help:



          ev4 = Eigenvalues[H[p, q, r, s]][[4]] /. 
          Thread[{p, q, r, s} -> {0.1, 0.5, 0.7, 0}];
          Plot3D[ev4, {x, -π, π}, {z, 0, 2 π}]


          enter image description here







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered 3 hours ago









          Michael E2Michael E2

          151k12203483




          151k12203483












          • $begingroup$
            Thanks @ Michael E2, Is it possible to do this with an equation by the contourplot. Like ev4 = Eigenvalues[H[p, q, r, s]][[4]] /. Thread[{p, q, r, s} -> {0.1, 0.5, 0.7, 0}]; ContourPlot[ev4==-0.5, {x, -[Pi], [Pi]}, {z, 0, 2 [Pi]}]. In my case this is not working.
            $endgroup$
            – Hazoor Imran
            2 hours ago










          • $begingroup$
            @HazoorImran Yes, but set the value -0.5 on the right hand side to something bigger. For example ContourPlot[ev4 == 2, {x, -[Pi], [Pi]}, {z, 0, 2 [Pi]}].
            $endgroup$
            – Michael E2
            2 hours ago










          • $begingroup$
            Thanks @ Michael E2, Yes this work.
            $endgroup$
            – Hazoor Imran
            2 hours ago


















          • $begingroup$
            Thanks @ Michael E2, Is it possible to do this with an equation by the contourplot. Like ev4 = Eigenvalues[H[p, q, r, s]][[4]] /. Thread[{p, q, r, s} -> {0.1, 0.5, 0.7, 0}]; ContourPlot[ev4==-0.5, {x, -[Pi], [Pi]}, {z, 0, 2 [Pi]}]. In my case this is not working.
            $endgroup$
            – Hazoor Imran
            2 hours ago










          • $begingroup$
            @HazoorImran Yes, but set the value -0.5 on the right hand side to something bigger. For example ContourPlot[ev4 == 2, {x, -[Pi], [Pi]}, {z, 0, 2 [Pi]}].
            $endgroup$
            – Michael E2
            2 hours ago










          • $begingroup$
            Thanks @ Michael E2, Yes this work.
            $endgroup$
            – Hazoor Imran
            2 hours ago
















          $begingroup$
          Thanks @ Michael E2, Is it possible to do this with an equation by the contourplot. Like ev4 = Eigenvalues[H[p, q, r, s]][[4]] /. Thread[{p, q, r, s} -> {0.1, 0.5, 0.7, 0}]; ContourPlot[ev4==-0.5, {x, -[Pi], [Pi]}, {z, 0, 2 [Pi]}]. In my case this is not working.
          $endgroup$
          – Hazoor Imran
          2 hours ago




          $begingroup$
          Thanks @ Michael E2, Is it possible to do this with an equation by the contourplot. Like ev4 = Eigenvalues[H[p, q, r, s]][[4]] /. Thread[{p, q, r, s} -> {0.1, 0.5, 0.7, 0}]; ContourPlot[ev4==-0.5, {x, -[Pi], [Pi]}, {z, 0, 2 [Pi]}]. In my case this is not working.
          $endgroup$
          – Hazoor Imran
          2 hours ago












          $begingroup$
          @HazoorImran Yes, but set the value -0.5 on the right hand side to something bigger. For example ContourPlot[ev4 == 2, {x, -[Pi], [Pi]}, {z, 0, 2 [Pi]}].
          $endgroup$
          – Michael E2
          2 hours ago




          $begingroup$
          @HazoorImran Yes, but set the value -0.5 on the right hand side to something bigger. For example ContourPlot[ev4 == 2, {x, -[Pi], [Pi]}, {z, 0, 2 [Pi]}].
          $endgroup$
          – Michael E2
          2 hours ago












          $begingroup$
          Thanks @ Michael E2, Yes this work.
          $endgroup$
          – Hazoor Imran
          2 hours ago




          $begingroup$
          Thanks @ Michael E2, Yes this work.
          $endgroup$
          – Hazoor Imran
          2 hours ago


















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