Why doesn't DSolve find all the solutions of this pde
- To: mathgroup at smc.vnet.net
- Subject: [mg72459] Why doesn't DSolve find all the solutions of this pde
- From: "Valeri Astanoff" <astanoff at gmail.com>
- Date: Fri, 29 Dec 2006 05:11:46 -0500 (EST)
Good day,
I wonder why DSolve doesn't find all the solutions
of this pde :
In[1]:=eq = r D[f[r,th],r] - Tan[2th] D[f[r,th],th] == 0;
In[2]:=DSolve[eq ,f[r,th],{r,th}]
>From In[2]:=
Solve::ifun Inverse functions are being used by Solve,
so some solutions may not be found; use Reduce
for complete solution information.
Out[2]={{f[r, th] -> C[1][Log[(-r)*Sqrt[Sin[2*th]]]]},
{f[r, th] -> C[1][Log[r*Sqrt[Sin[2*th]]]]}}
In[3]:=g[r_,th_] = r^2*Sin[2th];
In[4]:=eq/.f -> g
Out[4]=True
In[5]:=$Version
Out[5]=5.1 for Microsoft Windows (January 28, 2005)
With my early thanks for any advice
V.Astanoff
- Follow-Ups:
- Re: Why doesn't DSolve find all the solutions of this pde
- From: Devendra Kapadia <dkapadia@wolfram.com>
- Re: Why doesn't DSolve find all the solutions of this pde