People, I have been thinking about how to use Ruby for modelling populations - I want to use circles on a grid to represent the size of individual populations and determine if there is dispersal between pairs of populations by testing whether there is overlap with the two circles. I need to keep track of: - all the individual circles (populations) on a grid - which other circles each circle overlaps with And I need to: - iterate through ALL the circles (for each generation of the populations) I thought of using a two dimensional array, each row representing a circle. Elements 2-x of each row could point to another array representing the other circles that this circle overlaps with - but this seems fairly clumsy and was wondering if there is some better mechanism . . Thanks, Phil. -- Philip Rhoades Pricom Pty Limited (ACN 003 252 275 ABN 91 003 252 275) GPO Box 3411 Sydney NSW 2001 Australia Mobile: +61:(0)411-185-652 Fax: +61:(0)2-8221-9599 E-mail: phil / pricom.com.au