a field-theory motivated approach to computer algebra


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.
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