Plotting a bird using mathematical equation issue.

Question

Ahmed Mohamed Mansoor 2022-10-5

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评论： Ahmed Mohamed Mansoor 2022-10-5

Hello, I saw these set of equations that plot a bird using circles (See Image Below). I was able to code it down and the plot does not seem to be correct. However, there are a few issues with my code and it would be great if anybody could help.

My questions are:

The plot does not seem to be right when I run it (see image below). Can you please check if the code is correct to get the same plot as in the image above?
If I wanted to animate the plot, how would I do it?

clear; close all; clc;
A =@(k) sin((pi*k)./20000);
B =@(k) cos((31*pi*k)./10000);
C =@(k) sin((6*pi*k)./10000);
D =@(k) cos((31*pi*k)./10000);
E =@(k) sin((pi/2)*((k-10000)./(10000)).^7-(pi/5));
F =@(k) cos((pi/2)*((k-10000)./(10000)).^7-(pi/5));
G =@(k) sin((3*pi*k)./20000);
H =@(k) cos((3*pi)*((k-10000)./(100000)));
I =@(k) cos((9*pi)*((k-10000)./(100000)));
J =@(k) cos((36*pi)*((k-10000)./(100000)));
K =@(k) cos(((31*pi*k)./(10000))+((25*pi)/32));
L =@(k) cos((62*pi*k)./10000);
x = 1:9830;
% these are the Xk values 
Xk = A(x).^12 .* (0.5*B(x).^16.*C(x) + (1/6)*D(x).^20) + ((3*x)./20000) ...
    + B(x).^6 .*E(x);
% these are the Yk vlues
Yk = (-9/4)*B(x).^6.*F(x).*((2/3)+(A(x).*G(x)).^6) + ...
    (3/4)*H(x).^10.*I(x).^10.*J(x).^14 +...
    (7/10)*((x-10000)./(100000)).^2;
% This are the Rk values
Rk = A(x).^10.*((1/4)*K(x).^20 + (1/20)*B(x).^2) + (1/30).*((3/2)-L(x).^2);
figure()
scatter(Xk,Yk,[],Rk)
colormap(jet)

The plot looks like this:

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Answer 1

KSSV 2022-10-5

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在 MATLAB Online 中打开

You need to modify the radius Rk so that, it gives the look.

clear; close all; clc;

A =@(k) sin((pi*k)./20000);

B =@(k) cos((31*pi*k)./10000);

C =@(k) sin((6*pi*k)./10000);

D =@(k) cos((31*pi*k)./10000);

E =@(k) sin((pi/2)*((k-10000)./(10000)).^7-(pi/5));

F =@(k) cos((pi/2)*((k-10000)./(10000)).^7-(pi/5));

G =@(k) sin((3*pi*k)./20000);

H =@(k) cos((3*pi)*((k-10000)./(100000)));

I =@(k) cos((9*pi)*((k-10000)./(100000)));

J =@(k) cos((36*pi)*((k-10000)./(100000)));

K =@(k) cos(((31*pi*k)./(10000))+((25*pi)/32));

L =@(k) cos((62*pi*k)./10000);

x = 1:9830;

% these are the Xk values

Xk = A(x).^12 .* (0.5*B(x).^16.*C(x) + (1/6)*D(x).^20) + ((3*x)./20000) ...

+ B(x).^6 .*E(x);

% these are the Yk vlues

Yk = (-9/4)*B(x).^6.*F(x).*((2/3)+(A(x).*G(x)).^6) + ...

(3/4)*H(x).^10.*I(x).^10.*J(x).^14 +...

(7/10)*((x-10000)./(100000)).^2;

% This are the Rk values

Rk = A(x).^10.*((1/4)*K(x).^20 + (1/20)*B(x).^2) + (1/30).*((3/2)-L(x).^2);

figure()

scatter(Xk,Yk,Rk*8000,Rk)

colormap(jet)

axis equal

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Ahmed Mohamed Mansoor 2022-10-5

@Benjamin Thompson

Matter of fact. Yes. You were correct. Sorry about not considering your comment. and thank you for pointing that out.

Ahmed Mohamed Mansoor 2022-10-5

@KSSV

For example I tried to use comet but it did not seem to work.

Can I also ask another question. The beak of the bird at the very top seemes to be different from the actual piture. Any idea why this happens?

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Answer 2

Benjamin Thompson 2022-10-5

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The radius values Rk do not seem to be used properly. Are you calling scatter correctly? Looks like maybe you need three arguments instead of 4.

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Ahmed Mohamed Mansoor 2022-10-5

oh. I am still a little new to this. But from what I know the use of scatter is okay. The scatter function maps the elements in Rk to colors in the current colormap as far as I know.

But any help would do.

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