Editing Packing problems (section)

===Identical spheres in a cylinder===
{{main article|Sphere packing in a cylinder}}
People determine the minimum height {{mvar|h}} of a [[cylinder]] with given radius {{mvar|R}} that will pack {{mvar|n}} identical spheres of radius {{math|''r'' (< ''R'')}}.<ref>{{Cite journal | doi = 10.1111/j.1475-3995.2009.00733.x| title = Packing identical spheres into a cylinder| journal = International Transactions in Operational Research| volume = 17| pages = 51–70| year = 2010| last1 = Stoyan | first1 = Y. G. | last2 = Yaskov | first2 = G. N.}}</ref> For a small radius {{mvar|R}} the spheres arrange to ordered structures, called [[Columnar structure|columnar structures]].