Assumptions ignored?

*To*: mathgroup at smc.vnet.net*Subject*: [mg25061] Assumptions ignored?*From*: Jos R Bergervoet <Jos.Bergervoet at philips.com>*Date*: Thu, 7 Sep 2000 22:28:03 -0400 (EDT)*Organization*: Philips Research Laboratories*Sender*: owner-wri-mathgroup at wolfram.com

With the following input: Integrate[ x/Sqrt[x^2+zp^2]^3, {zp,z,Infinity}, Assumptions -> {x>0, z>0} ] I get: 2 2 2 Out[1]= x If[x + z >= 0 || Im[x ] != 0, .... Why does this if statement appear in the output? Why is Mathematica apparently ignoring my directive that x and z are positive? The same happens with Assumptions -> {x \[Element] Reals, z \[Element] Reals} and with combinations of these two versions. I would like to have the plain answer (without ifs and whens) to use it in further computations. How can it be obtained? (If possible, do not give answers about menus and mouseclicks, but just the lines of input to be typed. I'm not very fond of GUI's ;-) Thanks in advance, Jos -- Dr. Jozef R. Bergervoet Electromagnetism and EMC Philips Research Laboratories, Eindhoven, The Netherlands Building WS01 FAX: +31-40-2742224 E-mail: bergervo at natlab.research.philips.com Phone: +31-40-2742403