Talk:Functional integration

message: This page links to the disambiguation page Action. I'm not sure which page it's supposed to link to - I don't think it's Group action, which is the only vaguely mathematical page under Action. Could someone more knowledgeable fix the link to point directly to the appropriate page? Soo 22:42, 24 August 2006 (UTC)
thread_title:  Mathematical help wanted 

message: * Reading the first paragraph of the article 'Functional integration is a collection of results in mathematics and physics where the domain of an integral is no longer a region of space, but a space of functions. Functional integrals arise in probability, in the study of [b] partial differential equations [/b] and in Feynman's approach to the quantum mechanics of particles and fields', could someone provide any references of the fact of HOw the functional integrals are applied in the study of a general PDE?? —The preceding unsigned comment was added by Karl-H (talk • contribs) 20:38, 28 January 2007 (UTC)
replies: text: A functional integral is a method for computing the Green's function of a partial differential equation. The free particle functional integral is a formula for the Green's function of the diffusion equation in one dimension.  More interesting applications are the study of the symmetries of solutions of partial differential equations by using their functional integral representation, such as in the work by DeWitt-Morette.  —Preceding unsigned comment added by XaosBits (talk • contribs) 14:40, 28 June 2008 (UTC)
thread_title: A thing to be clarified??

message: In February 2010, User:Dr. Universe edited the second paragraph of this article to say that Functional integration was created "by P. J. Daniell in 1919 (in Annals of mathematics)". As far as I can tell from "But you have to remember P.J. Daniell of Sheffield" (linked from from Daniell's page), he did indeed have a role in the creation of functional integration and the relevant article is probably 
For the moment I'll just tidy up the text and will come back only if I get the chance to look more at this. –Syncategoremata (talk) 20:11, 13 March 2010 (UTC)
thread_title:  Functional integration and P.J. Daniell 

message: With regards to the "confusing" tag:
None of the notation given is explained, and will be unfamiliar or confusing to even those readers who are familiar with traditional calculus.
For example:
* What does G[f] do? What kind of object is it?
* What is Df and how is it analogous to `dx` in a traditional integral equation?
* What is df(x)? How is it different from whatever Df is?
* What is the capital Pi notation doing in this equation? Does it refer to the arithmetic product, or to function application in this context? Why is it there?
* How is the series of df(x) defined? Why is there a series at all? What are the bounds of the series (i.e. what values may x take)?
* What, exactly, takes on values between negative infinity to positive infinity? It is not clear what those extents "connect" to, given that the notation and meaning of the equation is altered in unspecified ways from a "traditional" integral.
To somebody not already completely familiar with this topic, the definition 
given is likely to read as ambiguous hieroglyphics, which share vague but 
impenetrable similarities to an ordinary integral. 
A better version of this article would explain what each object in the 
equation does, why it is there, and how it compares to the form and 
meaning of a traditional integral. Timrb (talk) 10:08, 15 January 2014 (UTC)
thread_title:  Definitions impenetrable for readers not familiar with subject