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Integral of BesselJ function doesn't calculate in my version?

Posted 2 years ago

Why the integral of BesselJ function multiplied by the power function does not calculated in Wolfram Mathematica?

POSTED BY: Elina Shishkina
4 Replies
$Version
(*"13.2.0 for Microsoft Windows (64-bit) (November 18, 2022)"*)

Integrate[BesselJ[\[Alpha], x*y]*x^\[Beta], {x, 0, Infinity}]

(* ConditionalExpression[(
 2^\[Beta] y^\[Alpha] Abs[y]^(-1 - \[Alpha] - \[Beta])
   Gamma[1/2 (1 + \[Alpha] + \[Beta])])/
 Gamma[1/2 (1 + \[Alpha] - \[Beta])], 
 y \[Element] Reals && Re[\[Beta]] < 1/2 && 
  Re[\[Alpha] + \[Beta]] > -1]*)

$\fbox{$\frac{2^{\beta } y^{\alpha } \Gamma \left(\frac{1}{2} (\alpha +\beta +1)\right) | y| ^{-\alpha -\beta -1}}{\Gamma \left(\frac{1}{2} (\alpha -\beta +1)\right)}\text{ if }y\in \mathbb{R}\land \Re(\beta )<\frac{1}{2}\land \Re(\alpha +\beta )>-1$}$

Regards M.I

POSTED BY: Mariusz Iwaniuk

Thank you. I know the answer. It can be found in INTEGRALS AND SERIES. Volume 2. Special Functions. By A.P. Prudnikov. Yu. A. Brychkov and O.I. Marichev. But still it is not calculated in my version 13.0 and in Wolfram Alpha also.

POSTED BY: Elina Shishkina

Probably Version issue. Maybe this helps:

Assuming[{Re[\[Beta]] < -1/2, Re[\[Alpha] + \[Beta]] > -1, Re[y] > 0}, Integrate[BesselJ[\[Alpha], x*y]*x^\[Beta], {x, 0, Infinity}]]
(* Or: *)
Integrate[BesselJ[\[Alpha], x*y]*x^\[Beta], {x, 0, Infinity}, Assumptions -> {Re[\[Beta]] < -1/2, Re[\[Alpha] + \[Beta]] > -1, Re[y] > 0}]
POSTED BY: Mariusz Iwaniuk

Yes, it is integrated with Assumptions. But usually these Assumptions are not known in advance. Thank you.

POSTED BY: Elina Shishkina
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