This routine returns the difference operator, in terms of the inert name LREtools[Delta], associated to the problem.  The operator is indexed by the name of the variable from the problem.

The command with(LREtools,REtodelta) allows the use of the abbreviated form of this command.

$\mathrm{with}\left(\mathrm{LREtools}\right)\:$

$\mathrm{REtodelta}\left(u\left(n+1\right)-u\left(n\right)\,u\left(n\right)\,\varnothing \right)$

${\left(\mathrm{LREtools}\left[\mathrm{\Delta }\right]\right)}_n$

$\mathrm{REtodelta}\left(\left(t+1\right)u\left(t+2\right)+\left(t+2\right)u\left(t\right)\,u\left(t\right)\,\varnothing \right)$

$\left(t+1\right){\left(\mathrm{LREtools}\left[\mathrm{\Delta }\right]\right)}_t^2+\left(2t+2\right){\left(\mathrm{LREtools}\left[\mathrm{\Delta }\right]\right)}_t+2t+3$