how can i create a cube represented by ones with a cylinder represented by zeros inside

I am wondering if somebody can help me create a cube (say NxNxN matrix of ones) which is simply a = ones(N, N, N) but will have a cylinder inside represented by zeros.

Basically, what i want is to have a 3D matrix that has ones and zeros representing the cube encapsulating the cylinder.

Thank you.

Answer 1

[Image Analyst]

use the FAQ to create a circle. http://matlab.wikia.com/wiki/FAQ?title=FAQ&cb=1158#How_do_I_create_a_circle.3F

Then use cat() or repmat() to replicate the 2d array as many times in the 3D direction as you need. It's easy - give it a try.

[Ping]

Thank you. But is there a way to avoid repmat() or cat()? SInce i was planning to extend the idea on having two or more cylinders intersecting inside the cube.

[Image Analyst]

Well those are the easiest ways, but you could just index everything to a plane in the z direction though I don't know why you'd want to do it that way since it's a little trickier. But how you extend into 3D vertically is totally unrelated to having two cylinders intersect, as long as they're parallel.