Hi everyone,
I already assume that there's a really trivial solution to this, but I just can't figure it out and also couldn't find anybody else writing about this - why is
In[1]:= Sin[x]/.Sin->Cos
Out[1]:= Cos[x]
but
In[1]:= A[x_]:=2x
B[x_]:=3x
A[x]/.A->B
Out[1]:= 2x
What's different with this replacement rule, and how to I get the desired result 3x?
