Re: making a parameter in an integrand real
- To: mathgroup at smc.vnet.net
- Subject: [mg116747] Re: making a parameter in an integrand real
- From: Peter Breitfeld <phbrf at t-online.de>
- Date: Sat, 26 Feb 2011 06:06:02 -0500 (EST)
- References: <ik84c3$n4v$1@smc.vnet.net>
alan wrote: > How do I get mathematica to consider a parameter in an integrand to be > real. > > Example: > In[1]:Integrate[1/(Cos[x] Sqrt[Cos[x]2 - a2]), x] > > ArcTanh[(Sqrt[2] Sqrt[-a2] Sin[x])/Sqrt[1 - 2 a2 + Cos[2 x]]]/Sqrt[- > a2] > > But I want a2>0 (a real). > > > > Use Assumptions or Assuming: Assuming[a > 0, Integrate[1/(Cos[x] Sqrt[Cos[x]^2 - a^2]), x] // Simplify ] Out= ArcTan[(Sqrt[2] a Sin[x])/Sqrt[1 - 2 a^2 + Cos[2 x]]]/a -- _________________________________________________________________ Peter Breitfeld, Bad Saulgau, Germany -- http://www.pBreitfeld.de