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Return-path: <Frederik.Orellana@cern.ch> Received: from rrzd2.rz.uni-regensburg.de [132.199.1.12] by gw.ngate.uni-regensburg.de; Tue, 23 Mar 2004 21:03:05 +0100 Received: from rrzd2 (rrzd2 [127.0.0.1]) by rrzd2.rz.uni-regensburg.de (8.12.3/8.12.3/Debian -4) with ESMTP id i2NK35j7032074 for <alessandro.bacchetta@physik.uni-regensburg.de>; Tue, 23 Mar 2004 21:03:05 +0100 Received: from rrzmx1.rz.uni-regensburg.de ([132.199.1.8]) by rrzd2 (MailMonitor for SMTP v1.2.2 ) ; Tue, 23 Mar 2004 21:03:05 +0100 (CET) Received: from smtp3.cern.ch (smtp3.cern.ch [137.138.131.164]) by rrzmx1.rz.uni-regensburg.de (8.12.3/8.12.3/Debian-6.6) with ESMTP id i2NK348C006010 for <alessandro.bacchetta@physik.uni-regensburg.de>; Tue, 23 Mar 2004 21:03:05 +0100 Received: from cern.ch (pcitapi34.cern.ch [137.138.167.144]) by smtp3.cern.ch (8.12.1-20030924/8.12.1) with ESMTP id i2NK2wqF020201 for <alessandro.bacchetta@physik.uni-regensburg.de>; Tue, 23 Mar 2004 21:02:58 +0100 (MET) X-Authentication-Warning: smtp3.cern.ch: Host pcitapi34.cern.ch [137.138.167.144] claimed to be cern.ch Message-ID: <406097F2.3050106@cern.ch> Date: Tue, 23 Mar 2004 21:02:58 +0100 From: Frederik Orellana <Frederik.Orellana@cern.ch> User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.2a) Gecko/20020910 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Alessandro Bacchetta <alessandro.bacchetta@physik.uni-regensburg.de> Subject: Re: documentation FeynCalc References: <405F08E7.2000007@physik.uni-regensburg.de> X-Enigmail-Version: 0.71.0.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit
Dear Alessandro.
Alessandro Bacchetta wrote: > Dear Frederik, > I am a (very basic-level) user of FeynCalc and I would like to know > if the new documentation is ready or when you plan to release it.
The book is basically finished, we just need some more worked through examples. Which is of course the time consuming part. Since Rolf and I have to earn a living too, both the development and documentation of FeynCalc goes in rather unpredictable bursts. We don't set ourselves hard deadlines as it would take much of the fun out of it. Sorry for that.
> At the moment, I have a very stupid problem but I don't know how to > get around it. In very simple terms, if I declare a vector to be > proportional to another one > > P= a V > > how can I tell FeynCalc that a is a scalar and V is a vector, so that > when I have contractions of the type > > GS[P] it is understood as: > a GS[V]?
In principle, MomentumExpand should be used. MomentumExpand pulls out variables for which NumberQ returns True.
So, you can set
NumberQ[a] ^= True;
Perhaps it is useful to dig a bit more into the internals of FeynCalc:
If you do
GS[v] // FCI // StandardForm
you'll get
DiracGamma[Momentum[v]]
GS is an *input function* or abbreviation. To get the full representation, FCI is used. To see the expression unformatted StandardForm is used.
Momentum is a head used to tag momentum variables. Usually its first argument is *one* variable, not a linear combination. Linear combinations should be made of the variables with head Momentum. Like
DiracGamma[b Momentum[v]]
In this case, DiracGamma itself pulls out b.
> > Thank you and sorry for the annoyment,
On the contrary, it is a pleasure to hear from people who use our stuff.
I would appreciate if you would forward this mail to feyncalc@feyncalc.org
> > Alessandro Bacchetta
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