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How to draw sectional plot for a 3D parameter equation?

Posted 2 years ago

Firstly, the Mathematica code is given as

A = -2/3000;
F = (7 Sinh[\[Xi] - 0.3 t])/(30 Cosh[\[Xi] - 0.3 t]) - (
   23 Sinh[\[Xi] - 0.3 t])/(60 (Cosh[\[Xi] - 0.3 t])^3) + (
   7 Sinh[\[Xi] - 0.1 t])/(15 Cosh[\[Xi] - 0.1 t]) - (
   23 Sinh[\[Xi] - 0.1 t])/(30 (Cosh[\[Xi] - 0.1 t])^3) - (
   7 Sinh[\[Xi] + 0.1 t])/(15 Cosh[\[Xi] + 0.1 t]) + (
   23 Sinh[\[Xi] + 0.1 t])/(30 (Cosh[\[Xi] + 0.1 t])^3) + 10;
FX = 0.3 (Sech[\[Xi] - 0.3 t])^2 + 0.5 (Sech[\[Xi] - 0.1 t])^2 - 
   0.8 (Sech[\[Xi] + 0.1 t])^2;
G = (7 Sinh[\[Eta]])/(30 Cosh[\[Eta]]) - (23 Sinh[\[Eta]])/(
   60 (Cosh[\[Eta]])^3);
GY = 0.3 (Sech[\[Eta]])^2;
func[\[Xi]_, \[Eta]_, t_] = (-3 FX*GY)/(2 A (F + G)^2);
With[{t = -25}, 
 With[{X = \[Xi] - 0.5 Tanh[\[Xi] - 0.3 t] - Tanh[\[Xi] - 0.1 t] - 
     1.5 Tanh[\[Xi] + 0.1 t], Y = \[Eta] - 1.15 Tanh[\[Eta]]}, 
  ParametricPlot3D[{X, Y, func[\[Xi], \[Eta], t]}, {\[Xi], 
    4, -10}, {\[Eta], 3, -3}, PlotRange -> All, Mesh -> None, 
   PlotPoints -> 100, ColorFunction -> "Rainbow", 
   AxesLabel -> {Style[x, {15}], Style[y, {15}]}]]]

and it comes

Fig. 1

Here, I would like to draw a 2D sectional plot for this 3D graphic at y=0, such as

Fig. 2

To achieve this goal, my code is

Y = 0;
With[{t = -25}, 
 With[{X = \[Xi] - 0.5 Tanh[\[Xi] - 0.3 t] - Tanh[\[Xi] - 0.1 t] - 
     1.5 Tanh[\[Xi] + 0.1 t]}, 
  ParametricPlot[{X, func[\[Xi], \[Eta], t]}, {\[Xi], 
    5, -10}, {\[Eta], 3, -3}, PlotRange -> All, Mesh -> None, 
   PlotPoints -> 100, AxesLabel -> {Style[x, {15}], Style[y, {15}]}]]]

and it comes

Fig. 3

How can I get the second picture(line sectional plot)?

cross-post: https://mathematica.stackexchange.com/questions/262040/how-to-draw-sectional-plot-for-a-3d-parameter-equation

POSTED BY: Lingfei Li

By plotting over the range {n,-3,3} you are plotting a parameteric region that contains all curves for -3<n<3.

You want to plot for Y=0

Plot[\[Eta] - 1.15 Tanh[\[Eta]], {\[Eta], -3, 3}]

Which is at n = 0

X[\[Xi]_, \[Eta]_, t_] := \[Xi] - 0.5 Tanh[\[Xi] - 0.3 t] - 
  Tanh[\[Xi] - 0.1 t] - 1.5 Tanh[\[Xi] + 0.1 t]
func[\[Xi]_, \[Eta]_, t_] = (-3 FX*GY)/(2 A (F + G)^2);
ParametricPlot[{X[\[Xi], 0, -25], func[\[Xi], 0, -25]}, {\[Xi], 
  5, -10}, PlotRange -> Full]

Or plot all the cureves

ParametricPlot[
 Evaluate[{X[\[Xi], #, -25], func[\[Xi], #, -25]} & /@ 
   Range[-3, 3, .5]], {\[Xi], 5, -10}, PlotRange -> Full]
POSTED BY: Martijn Froeling
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