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Re: PDE

• To: mathgroup at smc.vnet.net
• Subject: [mg42917] Re: [mg42801] PDE
• From: sean kim <shawn_s_kim at yahoo.com>
• Date: Sat, 2 Aug 2003 04:12:45 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

appears that the variables need to be in curly brackets. that's what
seems to be giving the option error.  

even with that fixed, it still gives me errors on how built in routines
can't solve it. 

when you are in mathematica start the help broswer. and type in error
message name to get more information on it. for instance, typing
NDSolve::pde into the search box gives you explanations on how to fix
them. 

hope that helps a little. 


In[6]:=
NDSolve[{D[QM[x, t], t] == 
      4x D[QM[x, t], x, x] + 6 D[QM[x, t], x] - 4.46 (QM - QB), 
    D[QB[x, t], t] == 1.911 (QM - QB), D[C[t], t] == 0.00005632 ( C -
CS), 
    Derivative[1, 0][QM][1, t] == 0.000047 (C - CS), QS == CS^1.17, 
    QM[x, 0] == 0, QB[x, 0] == 0, C[0] == 1, QM[1, t] == QS[t]}, { QM,
QB, C, 
    CS, QS}, {x, 0, 1}, {t, 0, 0.1}, AccuracyGoal -> Infinity, 
  PrecisionGoal -> 20, WorkingPrecision -> 25, MaxSteps -> 2000, 
  StartingStepSize -> 0.0001] 

above gives me, 

NDSolve::"pde": "Built-in routines cannot solve the partial
differential \
equation \!\({\(\[LeftSkeleton] 1 \[RightSkeleton]\)}\) ."

--- VASSILIOS MATSIS <vmats at tee.gr> wrote:
> Hi
> Could anyone help me with this problem?
> NDSolve[{D[QM[x, t], t] == 4x D[QM[x, t], x, x]
>         + 6 D[QM[x, t], x] - 4.46 (QM -
>             QB), D[QB[x, t], t] == 1.911 (QM - QB), D[C[t], t] ==
> 0.00005632
> (
>         C - CS), Derivative[1, 0][QM][1,
>     t] == 0.000047 (C - CS), QS == CS^1.17, QM[x, 0] == 0, QB[x, 0]
> == 0,
>     C[0] == 1, QM[1, t] == QS[t]}, QM, QB, C, CS, QS, {x, 0, 1}, {t,
> 0,
>     0.1}, AccuracyGoal -> Infinity, PrecisionGoal ->
>         20, WorkingPrecision -> 25, MaxSteps ->
>             2000, StartingStepSize -> 0.0001]
> NDSolve::"nonopt": "Options expected (instead of \!\({t, 0, 0.1`}\))
> beyond
> \
> position \!\(4\) in \!\(\[LeftSkeleton] 1 \[RightSkeleton]\). An
> option must
> \
> be a rule or a list of rules."
> 
> Thanks in advance
> 
> 


=====
when riding a dead horse,  some dismount.

while others... 

write memoirs on the subject of riding a dead horse.

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• Follow-Ups:
  • Re: Re: PDE
    • From: "Teodor Stanescu" <teodoor@hotmail.com>