Re: Another question on Assuming
- To: mathgroup at smc.vnet.net
- Subject: [mg85891] Re: Another question on Assuming
- From: dh <dh at metrohm.ch>
- Date: Wed, 27 Feb 2008 04:21:00 -0500 (EST)
- References: <fq0to0$k3s$1@smc.vnet.net>
Hi Kevin, the manual tells you that Assuming does nothing else than append the assumptions to $Assumptions and then evaluates expr. Your expression is Sqrt[a^2] that does not care about $Assumptions. Therefore, you need Refine that will care. hope this helps, Daniel Kevin J. McCann wrote: > The first example in the Mathematica Help on Assuming is (in part) > > Assuming[a > 0, Refine[Sqrt[a^2]]] > > which results in the answer a, as it should; however if I type instead > > Assuming[a > 0, Sqrt[a^2]] > > I get back Sqrt[a^2]], but I should get a, since there is no other > correct answer, because the assumption that a > 0 implies that it a is a > positive real. > > Bug? > > Kevin