Plot[Sin[1/t], {t, 0.00000000000000005, Pi/4}]

Plot3D[
      x^3 + y^3 - 3 x  - 12 y  + 20, {x, -8, 8}, {y, -8, 8}, 
      PlotPoints -> 60]

Plot3D[x^2 + y^2, {x, -10, 10}, {y, -10, 10}, 
      AspectRatio -> 1, 
      ViewPoint -> {1.611,  -2.974,  0.109}]

Plot3D[
      2 x^4 + y^2 - 3 x^2 y , {x, -10, 10}, {y, -3, 100}, 
      PlotPoints -> 100, 
      ViewPoint -> {1.418,  -3.060,  -0.279}]

Plot3D[
      Sin[x y] , {x, -5, 5}, {y, -5, 5}, 
      PlotPoints -> 100]

Plot3D[x^2 - y^2, {x, -10, 10}, {y, -10, 10}, 
      AspectRatio -> 1, 
      ViewPoint -> {1.611,  -2.974,  0.109}]

A = {{0, 1}, {-1, 0}}

    MatrixForm[A]

    MatrixForm[Transpose[A]]

    I2 = IdentityMatrix[2]

p[t_] = Det[A - t I2]

Solve[p[t] == 0, {t}]

B = {{2, 5}, {5, 14}}
p[t_] = Det[B - t I2]
Solve[p[t] == 0, {t}]
Eigenvalues[B]

G = {{3, 5, 7}, {5, 8, 34}, {7, 34, 100}}
MatrixForm[G]

N[Eigenvalues[G]]

Plot3D[Sin[x^2 + y^2], {x, -7, 7}, {y, -7, 7}, 
      PlotPoints -> 400]

Plot3D[(x^2 + y^2) Sin[x^2 + y^2], {x, -10, 10}, {y, -10, 
        10}, PlotPoints -> 500]

Plot3D[ Sin[x^2 + y^2], {x, -10, 10}, {y, -10, 10}, 
      PlotPoints -> 500, Mesh -> False, Shading -> True, 
      ViewPoint -> {0.021,  -0.040,  3.383}]

A = {{-4  x0^2, -4 x0 y0}, {-4 x0 y0,  -4 y0^2}}
MatrixForm[A]
Eigenvalues[A]

Plot3D[(x - 1)^4 + (x - y)^4, {x, -3, 5}, {y, -3, 5}, 
      PlotPoints -> 500, Mesh -> False]

Plot3D[
      200 ((x^2 + y^2))/((x^2 + y^2 + 1)^2)* 
        Sin[x^2 + y^2], {x, -10, 10}, {y, -10, 10}, 
      PlotPoints -> 500, Mesh -> False, 
      PlotRange -> {-200, 200}]

??  Plot3D