临界点作为几何中位数及其性质利用Hessian矩阵

临界点作为几何中位数及其性质利用Hessian矩阵
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2019-05-30 19:13
①本范例演示了如何通过GeoGebra绘制并分析函数的临界点作为几何中位数的性质;②涉及的核心数学概念包括临界点、Hessian矩阵、几何中位数、函数优化;③作图要点——使用了Polygon, PointIn, First, Sum, Sequence, Zip, TableText, Function, Length, Flatten, Textfield等命令和对象来构建图形和计算;④适合大学数学专业学生或对函数优化和几何性质感兴趣的学习者。

GeoGebra 命令及参数

  1. Polygon({((-π), ((-π)) / 2), ((-π), π / 2), (π, π / 2), (π, ((-π)) / 2)}) → q
  2. PointIn(q) → aP1
  3. PointIn(q) → aP2
  4. PointIn(q) → aP3
  5. PointIn(q) → aP4
  6. PointIn(q) → aP5
  7. PointIn(q) → aP6
  8. PointIn(q) → aP7
  9. PointIn(q) → aP8
  10. PointIn(q) → P9
  11. PointIn(q) → aP10
  12. First({P1, P2, P3, P4, P5, P6, P7, P8, P9, P10}, n) → lP
  13. PointIn(q) → A_2
  14. Sum(Zip[sqrt((x(a) - ((R * cos(x)) * cos(y)))^(2) + (y(a) - ((R * sin(x)) * cos(y)))^(2) + (z(a) - (R * sin(y)))^(2)), a, lP]) → f
  15. Sequence(If[D(i) > 0, If[f_{xx}(i) > 0, "local minimum", "local maximum"], If[(D(i) * f_{xx}(i)) ≟ 0, "?", "saddle point"]], i, 1, Length[l1]) → l4
  16. Zip((x(a), y(a)), a, l1) → l5
  17. TableText(Append["i", 1…Length[l1]], Append["critical points", l5], Append["f_{x}", lfx], Append["f_{y}", lfy], Append["f_{xx}", f_{xx}], Append["Det", D], Append["", l4], "v") → text1
  18. Function((q_f * f(u, v)) + b_0, u, (-π), π, v, ((-π)) / 2, π / 2) → f0
  19. Length(lsad) → läsad
  20. Length(lmax) → lämax
  21. Length(lmin) → lämin
  22. Zip(Segment[A, p], p, lP) → seg
  23. Sum(seg) → sum_seg
  24. Flatten(Sequence[Sequence[((-π) + ((2 * π / na) * i), ((-π)) / 2 + (π / na * j)), j, 1, na - 1], i, 1, na - 1]) → ltest_2
  25. Zip((R; x(a); y(a)), a, ltest_2) → ltest_3
  26. TableText(Append["i", Sequence[Length[lmax]]], Append["P_{Max }\;(φ,θ)", lmax], Append["(f'x,f'y)", lZf'xymax], "v") → textmax
  27. TableText(Append["i", Sequence[Length[(lmin * x)]]], Append["P_{Max }\;(φ,θ)", lmin], Append["(f'x,f'y)", lZf'xymin], "v") → textmin
  28. TableText(Append["i", Sequence[Length[(lsad * x)]]], Append["P_{Max }\;(φ,θ)", lsad], Append["(f'x,f'y)", lZf'xysad], "v") → textsad
  29. Textfield(R) → InputBox1
  30. Textfield(n) → InputBox2
  31. Textfield(lP0) → InputBox3