Mapping Diagram for Complex Integration over a Circle

Mapping Diagram for Complex Integration over a Circle
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2017-05-29 03:07
This GeoGebra example dynamically illustrates the mapping diagram for a complex integral along a circular path. It visualizes how points on the integration contour (a circle) are mapped by a complex function to the image plane, using vector fields and locus traces to show the Riemann-sum approximation of the integral. Core mathematical concepts include complex integration, parametrized curves, complex mappings, vector fields, and discretization of the integration path. Construction highlights: Sequence generates discrete sample points, Circle defines the contour, Line and Vector draw mapping arrows, Locus traces the image points, ToComplex converts coordinates to complex numbers, and Textfield/InputBox allow interactive input of the function and parameters. This is suitable for university-level complex analysis courses or advanced undergraduates, and serves as a powerful teaching tool for instructors to demonstrate the geometric meaning and numerical approximation of complex line integrals.

GeoGebra Commands & Parameters

  1. Sequence(0, n) → N
  2. Textfield(F) → InputBox1
  3. Expand(Simplify[F(x + (y * ί), 0, x(a_#) + (y(a_#) * ί), 0, x(b_#) + (y(b_#) * ί), 0)]) → Gz
  4. Zip(t_a + (k * dt), k, N) → t_*
  5. Zip((δ * ℯ^((t * ί))) + z_#, t, t_*) → z_*
  6. Circle(z_#, δ) → c
  7. Zip(Gr(x(z), y(z)) + (Gi(x(z), y(z)) * ί), z, z_*) → fz_*
  8. Zip((x(z), y(z), ht), z, fz_*) → gpt_*
  9. Line(O, ZS1) → Yax
  10. Line(O, ZR1) → Xax
  11. Zip(Vector[A, B], A, z_*, B, gpt_*) → gvec_*
  12. Vector(z_#, Gz1_#) → vecg_#
  13. Point(c) → A
  14. Locus(PtAG, A) → fLoc
  15. Sequence(Element[z_*, k + 1] - Element[z_*, k], k, 1, n) → dz
  16. Sequence((Element[fz_*, k] * Element[dz, k]), k, 1, n) → fdz_*
  17. Sequence(Sum[fdz_*, k], k, 1, n) → Sumfdz_*
  18. ToComplex(Sum[fdz_*, n]) → EstInt
  19. Zip(ToComplex[A], A, Sumfdz_*) → SumComx_*
  20. Zip((x(A), y(A), ht), A, SumComx_*) → Sumfdz3_*
  21. Zip(Vector[A, B], A, z_*, B, Sumfdz3_*) → SumVec_*
  22. Textfield(t_a) → InputBox2
  23. Textfield(t_b) → InputBox3