I was using a delayed rule to substitute a multi-variable derivative, but syntax error encountered in my second input as the following and the attachments. I am a Newbie. Is there anyone who would like to tell me what's wrong and how to fix it? Thanks a lot!
kc1 = -\!\(
\*SubscriptBox[\(\[PartialD]\), \(t\)]\(\[Eta][x, t]\)\) - U1 \!\(
\*SubscriptBox[\(\[PartialD]\), \(x\)]\(\[Eta][x, t]\)\) + \!\(
\*SubscriptBox[\(\[PartialD]\), \(y\)]\(
\(\*SubscriptBox[\(\[Phi]\), \(1\)]\)[x, y, t]\)\)
temp1 = kc1 /. {(\[Eta]^(a1_, a2_))[x, t] :> \!\(
\*SubscriptBox[\(\[PartialD]\), \({x, a1}, {t, a2}\)]\((
\*OverscriptBox[\(\[Eta]\), \(^\)] Exp[I\ k \((x - ct)\)])\)\)}
Attachments:
