How to rotate a function about the y-axis

2011 10 5
3 个回答
回答已采纳
5 次查看（30 天）

0 个投票

I wonder if anyone can help.
I have a Bessel function defined from x=0:20. I am trying to rotate it about the y-axis, so I can get a plot which resembles an Airy function.
I am struggling to write a for loop which will do this. Does anyone have a suggestion or pointers?
Thank you

6 个评论
显示 4更早的评论 隐藏 4更早的评论

Wayne King
Wayne King 2011-10-5
Hi Katy, please post the relevant MATLAB code so somebody can try to help you.
Jan
Jan 2011-10-5
Do you want to plot dots or a surface? For the later you can take a look into the source of SPHERE: Rotating around the Y-Axis is like drawing a deformed hemisphere.
Katy Pointer
Katy Pointer 2011-10-5
Hi Wayne; all I have at the moment is
x=[0.1:0.1:20];
J=besselj(1,x);
y=(J./x);
I don't even know how to get started trying to rotate it!
I want to end up with a matrix of values of height above the xy plane, so I can perform an fft on the result.
Thank you
Jan
Jan 2011-10-5
At first you asked for a method to plot the values. Now you want the results as a matrix. This is a different job.
Katy Pointer
Katy Pointer 2011-10-5
Isn't that the same thing? Then I can do mesh(matrix) to get the plot.
Jan
Jan 2011-10-5
You can plot a matrix. But rotating the Bessel function leads to a circular shape, not to a rectangular matrix.

请先登录，再进行评论。

请先登录，再回答此问题。

 采纳的回答

Teja Muppirala
Teja Muppirala 2011-10-5

1 个投票

Something like this maybe?
[X,Y]=meshgrid(-20:0.1:20);
R = sqrt(X.^2 + Y.^2);
J=besselj(1,R);
Z=(J./R);
Z(isnan(Z)) = 0.5; %Fix the divide by zero problem
surf(X,Y,Z);
shading flat;
camlight;

1 个评论
显示 -1更早的评论 隐藏 -1更早的评论

Katy Pointer
Katy Pointer 2011-10-5
That's amazing! Thank you. I had tried something similar, but didn't quite get the radius bit right. Thanks so much :)

请先登录，再进行评论。

类别

在 帮助中心 和 File Exchange 中查找有关 Bessel functions 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by