How to plot this feather using a mathematical equation

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Ahmed Mohamed Mansoor 2022-9-26

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1812160-how-to-plot-this-feather-using-a-mathematical-equation

评论： Ahmed Mohamed Mansoor 2022-9-27

I came across this image that intruiged me. It is a plot of a feather based on a mathematical equation. I attempted it, but couldn't get it right. Any idea how this could me done? I tried to use vectorisation method instead of a loop for now, but any method should be okay.

P.S: I'm still fairly new with MATLAB.

Here is the code I attempted

clear; close all; clc;
syms x y
f(x,y) = (-9/10) + ( 1 + (1/6) + ((1/(3*pi))*atan(30*( (3/50)-(y+(28/25)).^2 ))) )...
    .*(1-(((7*y)/10)+(2/10)).^10).*cos(x-(y/8)-(1/8)*(y+1).^2).^2000 ...
    +(1-sin((170*y)- 300*(x-(y/8)-(1/8)*(y+1).^2)^2 + (400/3)*(x-(y/8)-(1/8)*(y+1).^2)^3).^6)...
    .*((1/2)+((1/pi).*atan(400.*(1-(14.*(x-(1/20)-(y/8)-((1/8).*(y+1).^2).^2+(y.^2))).^2))));
figure()
fc = fcontour(f);
fc.LevelList = [0 0];

Would appreciate the help.

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采纳的回答

Davide Masiello 2022-9-26

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1812160-how-to-plot-this-feather-using-a-mathematical-equation#answer_1060760

编辑：Davide Masiello 2022-9-26

在 MATLAB Online 中打开

There:

clear,clc

[x,y] = meshgrid(linspace(-0.4,0.9,1000),linspace(-1.5,1.1,1000));

xy = x-y/8-(1/8)*(y+1).^2;

A = 1+1/6+atan(30*(3/50-(y+28/25).^2))/(3*pi);

B = 1-(7*y/10+2/10).^10;

C = 1-sin(170*y-300*xy.^2+(400/3)*xy.^3).^6;

D = 1/2+atan(400*(1-(14*(xy-1/20).^2+y.^2).^2))/pi;

f = -9/10 + A.*B.*cos(xy).^2000 + C.*D;

f(f>0) = 1;

f(f<0) = 0;

contourf(x,y,f,[0 1])

axis equal

map = [1 1 1 ; 0 0 0];

colormap(map)

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Davide Masiello 2022-9-27

The code as it it now plots everything all at once.

How exactly do you want to animate it?

Ahmed Mohamed Mansoor 2022-9-27

在 MATLAB Online 中打开

Yes you are correct.

Let's take a sin graph for example.

This is taken from the drawnow function documentation and it plots the points on a sing graph like an animation:

So would it possible to get it running like this?

clear; close all; clc;
h = animatedline;
axis([0 4*pi -1 1])
x = linspace(0,4*pi,2000);
for k = 1:length(x)
    y = sin(x(k));
    addpoints(h,x(k),y);
    drawnow
end