I have a function:
$\bar{u}:=u[t,x,y,z]$ (1)
How do I prevent it from expanding and substituting in instructions like those following:
$\partial _t {\bar u}$ (2)
Thanks in advance
EDIT: Mathematica expressions as asked:
OverBar[u]:=u[t,x,y,z]
D[ OverBar[u] , t]
Hold
,HoldForm
and related functions orDefer
? $\endgroup$