Subject: [newbie] Scalar field's eq. of motion (itensor)
From: Viktor T. Toth
Date: Tue, 9 Dec 2008 00:08:03 -0500
Try this:
load("itensor")$
imetric(g)$
ishow(L:-g([-u,-v],[])*covdiff(S([],[]),u)*covdiff(S([],[]),v)-m^2*S([],[])^
2)$
ishow( diff(L,S([],[])) - covdiff( diff(L, covdiff(S([],[]),l) ),l ) )$
%,ichr2$
flushd(%,g)$
ishow(rename(contract(%)))$
The fifth line evaluates ichr2 in terms of the metric; the sixth line
eliminates all terms that include (ordinary) derivatives of the metric; and
finally, the last line contracts and displays the result.
Viktor
-----Original Message-----
From: maxima-bounces at math.utexas.edu [mailto:maxima-bounces at math.utexas.edu]
On Behalf Of Victor Stabile
Sent: Monday, December 08, 2008 9:12 PM
To: maxima at math.utexas.edu
Subject: [newbie] Scalar field's eq. of motion (itensor)
Hi,
I want to calculate the free real scalar field's equation of motion (flat
space-time), so I go like:
load("itensor")
imetric(g)
ishow(L:-g([-u,-v],[])*covdiff(S([],[]),u)*covdiff(S([],[]),v)-m^2*S([],[])^
2)$
ishow( diff(L,S([],[])) - covdiff( diff(L, covdiff(S([],[]),l) ),l ) )$
Now the problem: covdiff is differentiating the metric. How can I avoid
that?
Thanks
Victor
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