弦振动问题演示

弦振动问题演示
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2019-04-24 11:35
①本范例演示了长度为L(此处L=1)的弦上波的演化过程,通过d'Alembert公式进行模拟;②涉及的核心数学概念包括偏微分方程、定积分、函数图像、几何变换等;③作图要点提炼自构造摘要,用到了对象t, D, E, F, G, f, ω, χ, ξ, μ, κ, η, ζ, γ, β, s, r, q, λ, h, g, ν, ϕ, ψ, p, f_1等GeoGebra命令;④适合高中及以上数学学习者,用于理解波动方程的数值解法及动态变化过程。

GeoGebra 命令及参数

  1. Numeric t(0.25)
  2. D(x) = x - floor(x)
  3. E(x) = (2 * D(x / 2))
  4. F(x) = E(x + t)
  5. G(x) = E(x - t)
  6. f(x) = If[0 ≤ F(x) ≤ 1 / 4, 0, 0]
  7. ω(x) = If[1 / 4 + 1 ≤ F(x) ≤ 1 / 2 + 1, (-4 * (F(x) - 2 + 3 / 4)), 0]
  8. χ(x) = If[1 / 4 + 1 ≤ G(x) ≤ 1 / 2 + 1, (-4 * (G(x) - 2 + 3 / 4)), 0]
  9. ξ(x) = If[1 ≤ G(x) ≤ 1 + 1 / 4, 0, 0]
  10. μ(x) = If[1 / 2 ≤ F(x) ≤ 3 / 4, (4 * (3 / 4 - F(x))), 0]
  11. κ(x) = If[1 / 2 + 1 ≤ G(x) ≤ 3 / 4 + 1, (4 * (1 / 4 - 2 + G(x))), 0]
  12. η(x) = If[1 ≤ F(x) ≤ 1 + 1 / 4, 0, 0]
  13. ζ(x) = If[3 / 4 + 1 ≤ G(x) ≤ 2, 0, 0]
  14. γ(x) = If[0 ≤ G(x) ≤ 0.25, 0, 0]
  15. β(x) = If[3 / 4 + 1 ≤ F(x) ≤ 2, 0, 0]
  16. s(x) = If[3 / 4 ≤ F(x) ≤ 1, 0, 0]
  17. r(x) = If[3 / 4 ≤ G(x) ≤ 1, 0, 0]
  18. q(x) = If[1 / 2 ≤ F(x) ≤ 3 / 4, (4 * (3 / 4 - F(x))), 0]
  19. λ(x) = If[1 / 2 + 1 ≤ F(x) ≤ 3 / 4 + 1, (4 * (1 / 4 - 2 + F(x))), 0]
  20. h(x) = If[1 / 2 ≤ G(x) ≤ 3 / 4, (4 * (3 / 4 - G(x))), 0]
  21. g(x) = If[1 / 4 ≤ G(x) ≤ 1 / 2, (4 * (G(x) - 1 / 4)), 0]
  22. ν(x) = If[1 / 4 ≤ F(x) ≤ 1 / 2, (4 * (F(x) - 1 / 4)), 0]
  23. ϕ(x) = r(x) + g(x) + h(x) + χ(x) + ξ(x) + κ(x) + ζ(x) + γ(x)
  24. ψ(x) = μ(x) + ν(x) + β(x) + ω(x) + η(x) + f(x) + s(x) + λ(x)
  25. p(x) = (1 / 2 * (ϕ(x) + ψ(x)))
  26. f_1(x) = If[0 ≤ x ≤ 1, p(x)]