Re: Vectorising circle drawing

[Jordi Gutiérrez Hermoso]

On 21/04/2008, address@hidden <address@hidden> wrote:
>    I have a matrix 'cr' where each row contains the center and radius
>  of a circle. Now, I want to draw these circles in a image.

Do you need to draw the interior of the circles? Are you tight on
memory? How about this idea, using repmat?

     cr = rand(2,10); #Row 1 is centres of circles, row is their radii.
     t = linspace(0,2*pi,100)';
     t = repmat(t,[1,columns(cr)]);
     c = repmat(cr(1,:),[rows(t),1]);
     r = repmat(cr(2,:),[rows(t),1]);
     circsx = r.*cos(t) + c;
     circsy = r.*sin(t) + c;
     plot(circsx,circsy);

This plots about 1000 circles on my machine in under three seconds
(dual-core Intel thingie).

Good?

- Jordi G. H.