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MathGroup Archive 1992

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Re: Question about changing variables in PDEs

  • To: mathgroup at yoda.physics.unc.edu
  • Subject: Re: Question about changing variables in PDEs
  • From: withoff
  • Date: Sat, 31 Oct 92 10:13:23 CST

-----------------
> I have a system of PDE's in in three dependent and two independent
>        variables.  For example:


>        { Dt[f,x] + f Dt[g,t] - f g,
          Dt[f,x,t] - Dt[h,x]^2,
          Dt[g,x] + Dt[h,t]}

> In[1]:= d = Dt[f,x] + Dt[g,x]

> Out[1]= Dt[f, x] + Dt[g, x]
 
> In[2]:= d /. Dt[y_,x] -> Dt[y,r]
 
> Out[2]= Dt[f, x] + Dt[g, x]
---------------------------

Try using Literal:

In[6]:= d = Dt[f,x] + Dt[g,x]
 
Out[6]= Dt[f, x] + Dt[g, x]
 
In[7]:= d /. Literal[Dt[y_,x]] -> Dt[y,r]

Out[7]= Dt[f, r] + Dt[g, r]
 
Dave Withoff
withoff at wri.com





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