The dot object is defined so that idiom like .[x,y] returns the
commutator, that is, (x*y-y*x)/2. The factor of 2 ensures that
.[x,y] == x %X% y.
The dot object is generated by running script inst/dot.Rmd,
which includes some further discussion and technical documentation,
and creates file dot.rda which resides in the data/
directory.
Value
Always returns an object of the same class as xy.
Arguments
x
Object of any class
i,j
elements to commute
...
Further arguments to dot_error(), currently ignored