Cadabra manual: Combine

combine

Combine two consecutive indexbracket objects

Combine two consecutive objects with indexbrackets and consecutive contracted indices into one object with an indexbracket. An example with two contracted matrices:

ex:=(\Gamma_r)_{\alpha\beta} (\Gamma_{s t u})_{\beta\gamma}; combine(_);

\(\displaystyle{}\left(\Gamma_{r}\right)\,_{\alpha \beta} \left(\Gamma_{s t u}\right)\,_{\beta \gamma}\)

\(\displaystyle{}\left(\Gamma_{r} \Gamma_{s t u}\right)\,_{\alpha \gamma}\)

An example with a matrix and a vector:

ex:=(\Gamma_r)_{\alpha\beta} v_{\beta}; combine(_);

\(\displaystyle{}\left(\Gamma_{r}\right)\,_{\alpha \beta} v_{\beta}\)

\(\displaystyle{}\left(\Gamma_{r} v\right)\,_{\alpha}\)

The inverse of combine is expand.