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 Author Comment/Response Andreas Veh 09/10/00 12:38pm Integrate[\[ExponentialE]^(-r/a), {r,0,\[Infinity]}] yields an If[Re(a)>0, ...] . I know that I could use Abs[a] instead and would get the evaluated integral. But I have more problems of that sort where I need to tell it ''Let a>0, ...''. E.g. Integrate[Exp[-r1]*r1^2*(Sqrt[(r1+r2)^2]-Sqrt[(r1-r2)^2])/r1/r2, {r1,0,Infinity}] which is not evaluated. The same integral can be rewritten: For r1<=r2, Integrate[Exp[-r1]*r1^2/r2, {r1,0,r2}] and for r1>=r2, Integrate[Exp[-r1], {r1,r2,Infinity}] which are evaluated. But how do I tell Mathematica ''For r1<=r2, Integrate[Exp[-r1]*r1^2*(Sqrt[(r1+r2)^2]-Sqrt[(r1-r2)^2])/r1/r2, {r1,0,r2}]'' etc.? URL: ,

 Subject (listing for 'How to write "Let a>0, ..."') Author Date Posted How to write "Let a>0, ..." Andreas Veh 09/10/00 12:38pm Re: How to write Ricardo 06/11/02 07:12am
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