I found some bizarre phenomena in my code. While I'm using Module in my function, the result is incompatible with which I did outside Module, and when I replaced Module with Block it went back to normal. I don't know why.
Edit:
Now the problem becomes this:
Module[{a,b}, a=Sin[x]; b[x_]=a; b[y] ] doesn't give Sin[y], while Block gives Sin[y].
ϕ[x_] = ϕxto makeϕa pure function failed, so all the followingϕs are function ofx. When I change toBlock, it seems fine again. Can you help me up with this? $\endgroup$Set @@ {b[x_], a}$\endgroup$