Rotating a 2D profile to make 3D

Question

Richard McCulloch 2014-3-25

1
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/122948-rotating-a-2d-profile-to-make-3d

评论： Richard McCulloch 2019-5-2

So I have a profile that I am rotating to make a 3D surface like this

a=0.661/0.511;
r=2.8179;
vo=1;
m=0.511;
theta=linspace(0,pi);
vp=vo./(1+a.*(1-cos(theta)));
dOmega=r^2/2.*(vp./vo).^2.*(vo./vp+vp./vo-sin(theta).^2);
figure
plot(dOmega.*cos(theta),dOmega.*sin(theta),'r','LineWidth',2)

Which produces the following plot

I am trying to make a surface using the cylinder command like this

[X,Y,Z] = cylinder(dOmega.*sin(theta)); 
figure 
surf(8.*Z,Y,X)

However, the profile negates the x-part of the 2D profile and instead of rounded ends it comes out pointy as shown below.

Does anyone know how to get around this? Thank you in advance for your help!

Richard

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Answer 1

Richard McCulloch 2014-3-25

4
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/122948-rotating-a-2d-profile-to-make-3d#answer_130148

在 MATLAB Online 中打开

OK, so I parametrized the functions and it worked out. Here is the completed code for those interested. It calculates the compton scattering cross section envelope at a specified gamma ray energy.

a=0.255/0.511;  
r=2.8179;       
vo=1;           
m=0.511; 
F = @(z)r^2/2.*((vo./(1+a.*(1-cos(z))))./vo).^2.*...
    (vo./(vo./(1+a.*(1-cos(z))))+...
    (vo./(1+a.*(1-cos(z))))./vo-sin(z).^2);
t = linspace(0,2*pi,55); 
z = linspace(0,pi,55); 
[T,U] = meshgrid(t,z); 
X = F(U).*sin(U).*cos(T); 
Y = F(U).*sin(U).*sin(T); 
Z = F(U).*cos(U); 
surf(Z,Y,X,X.^2+Y.^2+Z.^2)
shading interp
axis vis3d
axis equal
title('Differential Cross Section (10^{-26} cm^2/electron)')

This is the output

Richard

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Ragavendiran R 2019-5-2

Could you please explain the parameters a,r,m,vo and vp.

Richard McCulloch 2019-5-2

This is the Klein–Nishina formula for Compton Scattering angle calculations. For the purpose of this code a, r, m, and vo are just function constants. “The Atomic Nucleus” by R. Evans has a good treatment for a more detailed understanding.

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