Re: mixed partial derivatives
- To: mathgroup at smc.vnet.net
- Subject: [mg91278] Re: mixed partial derivatives
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Wed, 13 Aug 2008 04:39:42 -0400 (EDT)
- References: <g7rij3$i8v$1@smc.vnet.net>
Hi,
X[-3, v] == X[3, v]
will not work with mixed derivatives aspecial on the
interval u in [0,3] and not u in [-3,3]
and your equation is singular.
Regards
Jens
Narasimham wrote:
> When mixed derivatives are not allowed, what is the fix? TIA
>
> p=D[X[u,v],u]; q=D[X[u,v],v]; r =D[X[u,v],u,u]; s=D[X[u,v],u,v];
> t=D[X[u,v],v,v];
> GC[u_,v_] = (r t - s^2)/(1+p^2 + q^2)^2
> NDSolve[{GC[u,v]== 1, X[u, 0] == Cosh[u], Derivative[0,1][X][u, 0] ==
> 0,
> X[-3, v] == X[3, v]},X[u,v], {u,0,3},{v,0,3}]
>
> Narasimham
>