Revolving a curve around the z- axis

Hello there,

I'm new here, so I'll just get to it:

The intention is to generate path lines, which i can actually consider done with the underneath

[x,y]=meshgrid(-10:0.01:10,-10:0.01:10);r=sqrt(x.^2+y.^2);

z=log(r);

figure(1);

contour3(x,y,z,30)

Now in continuation of this, how do I plot stream lines with the description r=exp(z) or z=log(r) 12 times equally placed around the z-axis?

Answers would be very much appreciated, thank u.

Answer 1

[Star Strider]

The easiest way to do that would likely be to use the cylinder function —

x = -10:0.01:10;
y = -10:0.01:10;
r=sqrt(x.^2+y.^2);
z=log(r);

[X,Y,Z] = cylinder(z);

figure
contour3(X, Y, Z, 30)
grid on
colormap(turbo)

x = linspace(-10, 10, 30);
y = linspace(-10, 10, 30);
r=sqrt(x.^2+y.^2);
z=log(r);

[X,Y,Z] = cylinder(z);

figure
hm = mesh(X, Y, Z);
hm.MeshStyle = 'column';
grid on
colormap(turbo)

The contour3 plot however does not match my impression of what ‘streamlines’ would look like. The mesh plot could be another option.

.