Re: Integral giving complex answer
- To: mathgroup at smc.vnet.net
- Subject: [mg59279] Re: Integral giving complex answer
- From: mike_in_england2000 at yahoo.co.uk
- Date: Thu, 4 Aug 2005 02:08:01 -0400 (EDT)
- References: <dcples$6mm$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
David Sagan wrote: > Hello: > > I am tring to do simple integrals but I am running into problems in that > Mathematica gives the answer using complex numbers. For example, > Integrate[1/(1 + 5x^2), x] gives a result in terms of logarithms of a > complex argument instead of the usual arctan formula. If I integrate > something like Integrate[1/(1 + a x^2), x] I get the answer in the form > I want using the arctan. Hi David This probelm sounded interesting so I fired up Mathematica (I am using version 5.1 btw) , copied and pasted your integration command and got ArcTan[Sqrt[5]*x]/Sqrt[5] as the result. So i can't reproduce your problem. Which version of Mathematica are you using? Do you get this problem on a clean, newly opened notebook where the kernel has seen no previous calculations? Mike