{ "id": "1203.5191", "version": "v1", "published": "2012-03-23T07:25:36.000Z", "updated": "2012-03-23T07:25:36.000Z", "title": "On the convergence of double integrals and a generalized version of Fubini's theorem on successive integration", "authors": [ "Ferenc Moricz" ], "categories": [ "math.CA" ], "abstract": "Let the function $f: \\bar{\\R}^2_+ \\to \\C$ be such that $f\\in L^1_{\\loc} (\\bar{\\R}^2_+)$. We investigate the convergence behavior of the double integral $$\\int^A_0 \\int^B_0 f(u,v) du dv \\quad {\\rm as} \\quad A,B \\to \\infty,\\leqno(*)$$ where $A$ and $B$ tend to infinity independently of one another; while using two notions of convergence: that in Pringsheim's sense and that in the regular sense. Our main result is the following Theorem 3: If the double integral (*) converges in the regular sense, or briefly: converges regularly, then the finite limits $$\\lim_{y\\to \\infty} \\int^A_0 \\Big(\\int^y_0 f(u,v) dv\\Big) du =: I_1 (A)$$ and $$\\lim_{x\\to \\infty} \\int^B_0 \\Big(\\int^x_0 f(u,v) du) dv = : I_2 (B)$$ exist uniformly in $0