Replacing result with earlier variable definition

*To*: mathgroup at smc.vnet.net*Subject*: [mg115532] Replacing result with earlier variable definition*From*: Rakesh Dhote <rakesh.dhote at gmail.com>*Date*: Thu, 13 Jan 2011 03:30:26 -0500 (EST)

Hi, I am facing the following difficulty. I define "PE" in terms of "e" and perform some operations. I want to define the results in terms of "e" again. Please let me know, how to do it? Here is the dummy code for understanding: ================================================== In[1]:= Needs["VectorAnalysis`"] In[2]:= e=(D[u[x,y,t],x]-D[v[x,y,t],y])/Sqrt[2] Out[2]= (-(v^(0,1,0))[x,y,t]+(u^(1,0,0))[x,y,t])/Sqrt[2] In[3]:= PE=a1/2*e^4 Out[3]= 1/8 a1 (-(v^(0,1,0))[x,y,t]+(u^(1,0,0))[x,y,t])^4 In[4]:= H = D[PE,D[u[x,y,t],x]] Out[4]= 1/2 a1 (-(v^(0,1,0))[x,y,t]+(u^(1,0,0))[x,y,t])^3 In[5]:= Replace[H,(D[u[x,y,t],x]-D[v[x,y,t],y])/Sqrt[2]->e] (* To convert H in terms of e *) Out[5]= 1/2 a1 (-(v^(0,1,0))[x,y,t]+(u^(1,0,0))[x,y,t])^3 Now I would like to convert "H" in the terms of "e", which I defined earlier. I tried with Replace command, but didn't work. Please share your expertize. ================================================== Thanks a lot for your tips. Thanks, RD