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

% 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')

[Image Analyst]

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

Answer 1

[bio lim]

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')

Here is the updated graph.

Answer 2

[Adam Danz]

Starting in R2025a, polar axes support patch and surface objects.

Here's @bio lim's example applied to polar axes.

There's more info about patch and surface support in polar axes in the Graphics and App Building blog.

theta=linspace(0,2*pi,200);
radius=cos(5*theta);
radius(radius <= 0) = 0;

pax = polaraxes(); 
patch(pax,theta,radius,'blue',FaceAlpha=0.5)

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