From: "Bartosz DziewoƄski" Date: 2011-08-14T06:41:50+09:00 Subject: Re: Why this? For me, Math.hypot(10, 5)**2 is 125.00000000000001. Float numbers are simply not accurate; you should perform "fuzzy" comparisons - checking whether the difference between two floats is smaller than a hard-coded really small number. def fuzzy_eq a, b, eps = 1e-6 (a-b).abs < eps end -- Matma Rex