Try
eqn:ishow(td([],[i,j]) = canform(rename(expand(liediff(v,g([],[i,j]))))))$
instead of what you were using. The variable on the LHS of the assigment
must have the same free indices as the expression on the RHS.
(As a practical suggestion, unrelated to your problem, I often find it
useful to initialize the variable on the LHS as a matrix before running the
code produced by ic_convert. That is, do a td:zeromatrix(dim,dim) before
evaluating the code returned by ic_convert; this way, the result will be
stored as a matrix as opposed to a two-dimensional list.)
Viktor
-----Original Message-----
From: maxima-bounces at math.utexas.edu [mailto:maxima-bounces at math.utexas.edu]
On Behalf Of Leo Butler
Sent: Sunday, September 27, 2009 3:49 PM
To: 'Maxima List'
Subject: itensor -> ic_convert
In maxima I enter the following:
if get('itensor,'version)=false then load(itensor);
if get('ctensor,'version)=false then load(ctensor);
dim:3;
remcomps(g);
imetric(g);
eqn:ishow(td = canform(rename(expand(liediff(v,g([],[i,j]))))));
Which outputs
i %1 j %1 i j %1 j i
(%t32) td = - g v + v g - g v
,%1 ,%1 ,%1
(%o32) td = - g([], [i, %1]) v([], [j], %1) + v([], [%1]) g([], [i, j],%1)
- g([], [%1, j]) v([],
[i], %1)
Then I enter:
ic_convert(eqn);
Improper indices in - g([], [i, %1]) v([], [j], %1)
+ v([], [%1]) g([], [i, j], %1) - g([], [%1, j]) v([],
[i], %1)
Aside from the definition of eqn in terms of a Lie derivative, this is
the example from itensor8.dem, which works fine.
What am I doing wrong?
Leo
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