斜率场 by Doug Kuhlmann

GeoGebra 命令及参数

1. Sequence(Sequence[(xStart + ((i - 0.5) * xStep), yStart + ((j - 0.5) * yStep)), i, 1, n_x], j, 1, n_y) → GP1
2. Join(GP1) → GP
3. Length(GP) → NP
4. Sequence(sqrt(1 + Element[slp, k]^(2)), k, 1, NP) → len
5. Sequence(Segment[Element[GP, k] - ((Scale * 0.5) * (1, Element[slp, k]) / Element[len, k]), Element[GP, k] + ((Scale * 0.5) * (1, Element[slp, k]) / Element[len, k])], k, 1, NP) → Segs
6. Textfield(f) → DYDX
7. Textfield(Xmin) → xMin
8. Textfield(Xmax) → xMax
9. Textfield(Ymin) → yMin
10. Textfield(Ymax) → yMax
11. Textfield() → StartPoint
12. SolveODE(f, x(A), y(A), x(Corner[3]), Step) → ForwardA
13. Textfield() → Backward
14. SolveODE(f, x(A), y(A), x(Corner[4]), (-Step)) → BackA
15. If(togA ≟ 1, "Hide A & solution", "Show A & solution") → ShowA
16. Point(ForwardA) → B
17. If(togB ≟ 1, "Stop B", "Start B") → StartB