Dan DE handbook errata Fock
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A letter from Phil Lucht to Dan dated 6 March 2011 about a suspected error on page 351 (Section 78) of Dan's Differential Equations book, 3rd edition 1997. Phil argues the formula holds only for m = 0 and cites Oberhettinger and Higgins' tables of Mehler transforms. He restates the generalized Mehler-Fock transform pair, reduces it to the ordinary case, and notes a related reference on page 355. Some equations were lost in extraction.
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Hi Dan, 6 March 2011
While fumbling around with Mehler transforms, I think I spotted an obscure errata in your Differential Equations book, 3rd Edition 1997. I don't see it in your website errata list last updated Nov 22, 2000.
In Section 78 page 351 you have
I think this is only correct for m = 0, but I don't have Sneddon's book to check. However, right now I am staring at page 2 of F. Oberhettinger and T. P. Higgins, Tables of Lebedev, Mehler and Generalized Mehler Transforms, which is reference [21] on your page 355, and here is what I see:
In something I wrote a while ago, I presented the transform in this manner:
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The generalized Mehler-Fock (Mehler-Fok) transform (Oberhettinger and Higgins* page 2) is this,
g(y) = !Syntax Error, Idτ Pm-1/2+iτ(y) f(τ) // expansion
f(τ) = (τ/π) sh(πτ) Γ(1/2-m+iτ) Γ(1/2-m-iτ)!Syntax Error, Idy Pm-1/2+iτ(y) g(y) // projection
and for m = 0, using Γ(1/2+iτ)Γ(1/2-iτ) = π/cosh(πτ), one obtains the regular Mehler-Fock transform,
g(y) = !Syntax Error, Idτ P-1/2+iτ(y) f(τ) // expansion
f(τ) = τ th(πτ)!Syntax Error, Idy P-1/2+iτ(y) g(y) // projection
which can also be written as
G(ξ) = !Syntax Error, Idτ P-1/2+iτ(chξ) f(τ) // expansion
f(τ) = τ th(πτ) !Syntax Error, Idξ shξ P-1/2+iτ(chξ) G(ξ) // projection
* F. Oberhettinger and T. P. Higgins, Tables of Lebedev, Mehler and Generalized Mehler Transforms, (Boeing Scientific Research Laboratories, Mathematical No. 246, 1961). A 48 page monograph with about 16 transforms per page. The first author is a member of A. Erdelyi et. al mentioned above. We obtained this book by interlibrary loan from the Coe library at the University of Wyoming.
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As another piece of evidence, here is a clip from your page 355 Nasim reference [19] :
You can set σ = 0 and t = ix to get something equivalent to Oberhettinger and Higgins.
Best regards,
Phil Lucht
Salt Lake City