How can I fill with color a odd flower in a cartesian o polar coordinates?

Question

Marcos Perez 2015-7-8

1
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/228976-how-can-i-fill-with-color-a-odd-flower-in-a-cartesian-o-polar-coordinates

编辑： bio lim 2015-7-8

% In rectangular coordinates
theta=linspace(0,2*pi,200);
radius=cos(5*theta);
x=radius.*(cos(theta));
y=radius.*(sin(theta));
fill(x,y,'b') % when matlab run, only fill with color not odd flowers
axis('square')
% In polar coordinates
p=Polar(theta,radius,'-b')
patch(get(ph,'XData'), get(ph,'YData'), 'b')

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Image Analyst 2015-7-8

I fixed your formating, and am attaching the screenshot you forgot to include:

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

bio lim 2015-7-8

3
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/228976-how-can-i-fill-with-color-a-odd-flower-in-a-cartesian-o-polar-coordinates#answer_185347

编辑：bio lim 2015-7-8

在 MATLAB Online 中打开

As a matter of fact, you are filling with color. What you are filling are the small polygons as shown in the figure below.

If we look closely, we can see the small polygons that are filled with blue colour.

The fill() and patch() works perfectly when you are dealing with even number of petals. However, even for even petals, if you zoom in closely at the center, you can see that there are regions which are not filled.

I think the problem with your code is that when the radius takes less than 0 value, the polygons occur. So a simple solution would be:

theta=linspace(0,2*pi,200);
radius=cos(5*theta);
radius(radius <= 0) = 0;
x=radius.*(cos(theta));
y=radius.*(sin(theta));
fill(x,y, 'b');
axis('square')