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+3 votes

Hi! I am new to Cadabra and faced the following issue with contraction of indices.

Define a metric in dimension N as follows

g_{i j}::Metric;
g^{i j}::InverseMetric;

Now, if I run

_:= g_{i}^{i}:

the output is (as expected) N

On the other hand, if I set up an equation, it appears not to work.

_:= N = g_{i}^{i}:

In this case, the output is


and the contraction is not simplified on the right hand side of the equation.

Any help will be appreciated!

in General questions by (320 points)

1 Answer

+2 votes
Best answer

That's a bug, thanks for reporting it. Try

_:= N = g_{i}^{i} + 1

It's the edge-case of a single term with a single factor on the rhs which is not handled correctly. Will fix.

by (71.9k points)
selected by

Now fixed on github.