A geometric interpretation of a function of a complex variable with Mathematica?

How to write code in math to see the result as follows:

enter image description here

As you can see, we have a complex function w=f(z) , where z=x+iy and w=u+iv .

In this example, w=sin z , and we see that the image of the vertical line x=c is a hyperbola. (Left)

and the image of the horizontal line y=c is elliptical. (On right)

This picture is taken from the book “Complex Variables and Applications” by James Ward Brown, Ruel Vance Churchill, 8th edition: pages 331 and 333 or pages of the third edition 96-97

+4
source share
2 answers

Something like that?

 ClearAll[u, v, f]; f[z_] := Sin[z] u[x_, y_] := Re@f [x + I*y]; v[x_, y_] := Im@f [x + I*y]; 

enter image description here

EDIT: It just produces everything. If you just want to see what happens for one path parallel to an imaginary axis, try

 ParametricPlot[{u[5, y], v[5, y]}, {y, -3, 3}] 

or for the same parallel with the real try axis

 ParametricPlot[{u[x, 1], v[x, 1]}, {x, -3, 3}] 

EDIT2: Interactive:

 ClearAll[u, v, f]; f[z_] := Sin[z] u[x_, y_] := Re@f [x + I*y]; v[x_, y_] := Im@f [x + I*y]; Manipulate[ Show[ Graphics[{Line[{p1, p2}]}, PlotRange \[Rule] 3, Axes \[Rule] True], ParametricPlot[ {u[p1[[1]] + t (p2[[1]] - p1[[1]]), p1[[2]] + t (p2[[2]] - p1[[2]])], v[p1[[1]] + t (p2[[1]] - p1[[1]]), p1[[2]] + t (p2[[2]] - p1[[2]])]}, {t, 0, 1}, PlotRange \[Rule] 3]], {{p1, {0, 1}}, Locator}, {{p2, {1, 2}}, Locator}] 

(ugly, yes, but time cannot be fixed). Typical Output: enter image description here

or

enter image description here

The idea is that you can change the line on the left side of the figures that you give (by clicking on the plot, which is a click on the Argand diagram ...) and see the corresponding images.

+3
source

Depending on what you want to do with the views, it can sometimes be useful to render the Riemann surface in 3D. Here is the surface for w=sin(z) in 3D, neatly showing sections of branches and different branches (the same as the first acl plot, but in 3D).

 ParametricPlot3D[ Evaluate[{ Re@Sin [z], Im@Sin [z], y} /. z -> x + I y], {x, -2, 2}, {y, -2, 2}] 

enter image description here

+2
source

All Articles