Talk:Riemann–Liouville integral

Font for differential operator
This page uses the blackboard bold font ($$\mathbb{D}$$) for the differential operator rather than a normal D. I have never seen this notation before. Is it standard? If not, I will change it (unless someone else beats me to it). --ComplexZeta 18:34, 2004 Dec 30 (UTC)

I started that on these pages (i started these pages), and it's for two reasons: 1. Because from my experience, that is one of the standrds. I could be wrong, and 2. Because it's clear and obvious, imho - more clear than a normal D, which could be just a variable (ABCD); it's clear that it's an operator. Kevin Baastalk 18:54, 2004 Dec 30 (UTC)

Can you point me to some books/articles/websites in which this notation is used? Thanks. --ComplexZeta 18:57, 2004 Dec 30 (UTC)


 * I was just looking through the internet links, and I couldn't find any instances. I might have come across it in some papers, I don't know.  I've personally acquired an affinity for it, but I currently can't provide any evidence that it's a standard. Kevin Baastalk 19:02, 2004 Dec 30 (UTC)


 * It appears that this notation is idiosyncratic. Kevin Baastalk

Complex order?
I see a hint that the q may be complex. If so we'll need a complex ceiling definition, like $$\lceil q\rceil\in\mathbb Z$$ s.t. $$\lceil q\rceil\ge\Re q>\lceil q\rceil-1$$

Otherwise that first box needs to be changed. (BTW forgive my drastic change of notation in the Caputo addition but that diddle-surrounded BB D is ugly, "idiosyncratic," and should be cleaned.) Kwantus 2005 July 2 19:51 (UTC)

Merge "Differintegral" into this page and RD
The page Differintegral exists and mirrors this page. As this page is more correctly titled the content of that page should be merged into this page. The two pages are both fairly complete, but are redundant and should be unified. A redirect at "Differintegral" to "Riemann-Liouville differintegral" would be appropriate on that page. --Matthew 19:02, 9 March 2006 (UTC)

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On the origin
According to the article on fractional calculus, Niels Henrik Abel was the first to define this integral with noninteger parametr, in 1823, and used it to solve his Abel Integral Equations in 1826. This is in contradiction with what this article states, viz. that Liouville was the first to consider this integral 92.221.229.69 (talk) 16:18, 24 June 2023 (UTC)