The other day I asked for help in evaluating a definite integral Let h = 1/2, to save space. Int_{x = 0..h} Int_{r=-h-x..h-x} Int_{y=0..h} Int_ {s=-h-y..h-y} sqrt(r^2+s^2) dx dr dy ds = ? Thanks to David Cantrell, Eric Weisstein, Steve Finch, Emeric Deutsch and others who replied. To summarize the results: Integrals like this can be found in the books Finch, Encyclop. of Math. Constants (CUP); Santalo, Integral Geometry (Addison-Wesley) There is a web page in Spanish: <http://groups.google.com/group/es.ciencia.matematicas/browse_frm/thread/efec... d222ada58ab7> Mathematica can do this integral, but you have to put the variables in the right order, and you need a machine with the right operating system (it worked on a Sun Linux 64-bit machine, but - with the same version of Mma - failed on an Intel-based Linux 64-bit machine) Best regards Neil