Re: Integer Assumptions in Integrations

*To*: mathgroup at smc.vnet.net*Subject*: [mg20189] Re: Integer Assumptions in Integrations*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Tue, 5 Oct 1999 04:04:19 -0400*Organization*: Universitaet Leipzig*References*: <7t4ctm$82s@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi, your 'a' does not matter the result of the integration Mathematica 4.0 return : In[25]:= Integrate[t^(a - 1)*Exp[-t], {t, q, Infinity}] Out[25]= Gamma[a, q] and Mathematica 3.0.1 Integrate[t^(a-1)*Exp[-t], {t, q, Infinity},Assumptions->{q>0}] Gamma[a, q] In Mathematica 4.0 you can still using Simplify[_,Element[a,Integers]], FullSimplify[_,Element[a,Integers]]. Hope that helps Jens Will Cooper wrote: > > Hello, > How can I set a variable assumption to be an integer in an integration > calculation? > > e.g. The incomplete gamma function is defined as Gamma[a,q] = > Integrate[t^(a-1)*Exp[-t], {t, q, Infinity}] > > I want to set the assumption that 'a' is always an Integer. > > I don't want to round 'a' to the next lowest integer, i.e. > Integrate[t^(Integer[a]-1)*Exp[-t], {t, q, Infinity}] > > I just want to indicate that 'a' only assumes integer values. > > Thanks for any assistance. > > Will Cooper.