Plotting a multi-function surface?
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I have the following system:
f = ln(1/x) + 3 for when 1<x
f = 3 for when 0<=x<=1
What I want to do is effectively plot this 2D system as a surface in cylindrical coordinates, 'spinning' the line round as to create something resembling a flat-topped cone. Unfortunately, my limited knowledge of of both the surf and mesh functions leave me unsure of how to do this. Any help would greatly appreciated. Thanks.
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Star Strider
2015-11-9
Is this what you want to do? If not, experiment with it. This should get you started.
f = @(x) 3.*((x >= 0) & (x <= 1)) + (log(1./x) + 3).*(x > 1); % Function
x = linspace(0, 5, 25); % Change upper Limit & Vector Length
[Xc,Yc,Zc] = cylinder(f(x), 25); % Create Cylinder With ‘f’ Describing Radius
figure(1)
surf(Xc, Yc, Zc) % Plot Resulting Cylinder
grid on
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Jack Smith
2015-11-9
Thanks. This is great, but what I'm trying to do is 'spin' this round:
Star Strider
2015-11-9
It took me a while to figure out how to invert that. In the end it was straightforward (but then everything is in retrospect):
f = @(x) 3.*((x >= 0) & (x <= 1)) + (log(1./x) + 3).*(x > 1); % Function
finv = @(x) exp(f(x));
x = linspace(0, 20, 25); % Change upper Limit & Vector Length
[Xc,Yc,Zc] = cylinder(finv(x), 25); % Create Cylinder With ‘f’ Describing Radius
figure(1)
surf(Xc, Yc, 3.1*Zc) % Plot Resulting Cylinder
grid on
axis equal
It doesn’t look exactly like your posted plot because I set axis equal so that I could verify it. Your plot would look like a cross-section of mine if you did the same on your plot.
Jack Smith
2015-11-10
Star Strider
2015-11-10
My pleasure!
That was definitely a challenge!
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