如何在 MATLAB 中绘制类贝塞尔函数
我对 MATLAB 完全陌生，只知道一些基本命令。我的任务是绘制一个这样的函数：
I(T) = ((2*J(k*r*sin(T))/(k*r*sin(T))))^2
我在这里
T = angle
k = (2*pi*f)/c (f= frequency in Hz and c is speed of sound)
r = radius
J = bessel function first kind
解释一下：该函数代表空间中声波的功率。我已经尝试了很多次来绘制这个图，但我总是在图中得到一个点。
I'm totally new to MATLAB and I know only few basic commands. My task is to plot a function of this kind:
I(T) = ((2*J(k*r*sin(T))/(k*r*sin(T))))^2
where
T = angle
k = (2*pi*f)/c (f= frequency in Hz and c is speed of sound)
r = radius
J = bessel function first kind
I explain a bit: the function represent the power of a soundwave in the space. I've tried many times to plot this but i get always a single point in the plot.
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评论（3）
我假设您已经在
J中定义了贝塞尔函数。如果不是，则第一类 Bessel 函数的 MATLAB 命令为besselj。您还必须指定贝塞尔函数的阶数。您可以将匿名函数定义为
并将其绘制为
I assume you've defined your Bessel function in
J. If not, the MATLAB command for a Bessel function of the first kind isbesselj. You'll also have to specify the order of the Bessel function.You can define your anonymous function as
and plot it as
怎么样
what about
我终于找到了如何管理上述问题，这是我找到的解决方案，以防其他人可能需要它。
% 类似贝塞尔函数的图形生成的 MATLAB 指令 %
% 变量（固定值）%
k = 912.91
r = 0.0215
% 设置角度 theta % 的范围
theta = (-(2/3)*pi:pi/180:(2/3)*pi)
% 第一类贝塞尔函数的计算 %
J = besselj(1,k*r*sin(theta))
% 计算 I 函数 %
% 注意 ./ 和 .^ 运算符
I = ((2*J)./(k*r*sin(theta))).^2
% 现在使用绘图命令绘制结果
情节（θ，I）
I finally found how to manage the problem described above, here's the solution that i found, in case that other people may need it.
% MATLAB Istruction for graph generation of bessel like function %
% Variables (fixed values)%
k = 912.91
r = 0.0215
% Set the range for the angle theta %
theta = (-(2/3)*pi:pi/180:(2/3)*pi)
% Calculation of bessel function of first kind %
J = besselj(1,k*r*sin(theta))
% Calculation I function %
% notice the ./ and .^ operators
I = ((2*J)./(k*r*sin(theta))).^2
% now plot the results with the plot command
plot(theta,I)