Drawing a segment of a circle

I would like to draw a segment of a circle (like a slice of a pizza) but cannot find an easy way to do it.

I am currently drawing triangles using fill function but ideally I need one side of the triangle to be curved. Is there a way to specify a curvature of a line? Thanks B

Answer 1

[the cyclist]

There are several files in the File Exchange that will do what you want. Here is one:

http://www.mathworks.com/matlabcentral/fileexchange/25580-ellipse

Also, here is a simple function that could be modified to draw just a segment:

function h = circle(x,y,r,nsegments)  

if nargin<4
    nsegments=50;
end

hold on
th = 0:2*pi/nsegments:2*pi;
xunit = r * cos(th) + x;
yunit = r * sin(th) + y;
h = plot(xunit, yunit);
hold off

end

[poonam tailor]

Sir i need sector's center point. As i need a mid region of a circles sector for cluster head selection.

Answer 2

[Matt Fig]

Here is another function to do it. It returns the handle to the patch object so that the color can be set or whatever.

function P = plot_arc(a,b,h,k,r)
% Plot a circular arc as a pie wedge.
% a is start of arc in radians, 
% b is end of arc in radians, 
% (h,k) is the center of the circle.
% r is the radius.
% Try this:   plot_arc(pi/4,3*pi/4,9,-4,3)
% Author:  Matt Fig

t = linspace(a,b);
x = r*cos(t) + h;
y = r*sin(t) + k;
x = [x h x(1)];
y = [y k y(1)];
P = fill(x,y,'r');
axis([h-r-1 h+r+1 k-r-1 k+r+1]) 
axis square;

if ~nargout
    clear P
end

Now from the command line:

P = plot_arc(pi/4,3*pi/3,9,-4,3);
set(P,'edgecolor','b','linewidth',4)

[Bojan]

Thank you very much

[Bojan]

Another question, how can you add colour to the face of the pie wedge?

[Matt Fig]

Simply use FILL instead of PLOT.

[Matt Fig]

See my edited code above...

[Bojan]

Perfect, exactly what I need

B

[Ron Beck]

Is it possible to have a curve at the bottom instead of a point?

[zain ul haq]

Sir, can I plot the segmet with height too, I need to plot like a 3d slice of a cake