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Difference between revisions of "Hardy transform"

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The integral transform
 
The integral transform
  
<table class="eq" style="width:100%;"> <tr><td valign="top" style="width:94%;text-align:center;"><img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/h/h046/h046390/h0463901.png" /></td> </tr></table>
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$$F(x)=\int\limits_0^\infty C_\nu(xt)tf(t)dt,$$
  
 
where
 
where
  
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$$C_\nu(z)=\cos p\pi J_\nu(z)+\sin p\pi Y_\nu(z),$$
  
and <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/h/h046/h046390/h0463903.png" /> and <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/h/h046/h046390/h0463904.png" /> are the [[Bessel functions|Bessel functions]] of the first and second kinds, respectively. For <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/h/h046/h046390/h0463905.png" /> the Hardy transform coincides with one of the forms of the Hankel transform, and for <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/h/h046/h046390/h0463906.png" /> with the <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/h/h046/h046390/h0463907.png" />-transform. The Hardy transform was proposed by G.H. Hardy in [[#References|[1]]].
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and $J_\nu(z)$ and $Y_\nu(z)$ are the [[Bessel functions|Bessel functions]] of the first and second kinds, respectively. For $p=0$ the Hardy transform coincides with one of the forms of the Hankel transform, and for $p=1/2$ with the $Y$-transform. The Hardy transform was proposed by G.H. Hardy in [[#References|[1]]].
  
 
The inversion formula is
 
The inversion formula is
  
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$$f(t)=\int\limits_0^\infty\Phi(tx)xF(x)dx,$$
  
 
where
 
where
  
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$$\Phi(x)=\sum_{n=0}^\infty\frac{(-1)^n(x/2)^{\nu+2p+2n}}{\Gamma(p+n+1)\Gamma(\nu+p+n+1)}.$$
  
 
The Hardy transform is also defined for certain classes of generalized functions.
 
The Hardy transform is also defined for certain classes of generalized functions.

Latest revision as of 17:37, 1 August 2014

The integral transform

$$F(x)=\int\limits_0^\infty C_\nu(xt)tf(t)dt,$$

where

$$C_\nu(z)=\cos p\pi J_\nu(z)+\sin p\pi Y_\nu(z),$$

and $J_\nu(z)$ and $Y_\nu(z)$ are the Bessel functions of the first and second kinds, respectively. For $p=0$ the Hardy transform coincides with one of the forms of the Hankel transform, and for $p=1/2$ with the $Y$-transform. The Hardy transform was proposed by G.H. Hardy in [1].

The inversion formula is

$$f(t)=\int\limits_0^\infty\Phi(tx)xF(x)dx,$$

where

$$\Phi(x)=\sum_{n=0}^\infty\frac{(-1)^n(x/2)^{\nu+2p+2n}}{\Gamma(p+n+1)\Gamma(\nu+p+n+1)}.$$

The Hardy transform is also defined for certain classes of generalized functions.

References

[1] G.H. Hardy, "Some formulae in the theory of Bessel functions" Proc. London. Math. Soc. (2) , 23 (1925) pp. 61–63
[2] Y.A. Brychkov, A.P. Prudnikov, "Integral transforms of generalized functions" , Gordon & Breach (1989) (Translated from Russian)
How to Cite This Entry:
Hardy transform. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Hardy_transform&oldid=32672
This article was adapted from an original article by Yu.A. BrychkovA.P. Prudnikov (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article