Using assumptions with Integrate

Asked Apr 22 '16 at 11:20

Active Apr 22 '16 at 16:05

Viewed 42 times

I open Mathematica and execute this code:

Integrate[BesselJ[0, s*x], {x, 0, Infinity}, Assumptions -> s ∈ Reals]
(* MMA can't integrate this *)

Assuming[s ∈ Reals, Integrate[BesselJ[0, s*x], {x, 0, Infinity}]]
(* Output->1/Abs[s] *)

Also

Integrate[BesselJ[0, s*x], {x, 0, Infinity}, Assumptions -> s > 0]
(* MMA can't integrate this *)

Assuming[s > 0, Integrate[BesselJ[0, s*x], {x, 0, Infinity}]]
(* Output->1/s *)

$Version
(* 10.2.0 for Microsoft Windows (64-bit) (July 7, 2015) *)

edited Apr 22 '16 at 16:05

m_goldberg

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asked Apr 22 '16 at 11:20

Mariusz Iwaniuk

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Possible duplicate: http://mathematica.stackexchange.com/a/19894/ – Michael E2 Apr 22 '16 at 11:31
It works for me, though takes about a minute to calculate (Win7 Mma10.4.1) – Alexei Boulbitch Apr 22 '16 at 12:08
@MichaelE2. Now I am even more confused............Thanks. – Mariusz Iwaniuk Apr 22 '16 at 12:58

Using assumptions with Integrate

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