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MathGroup Archive 2007

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Re: Solve[] and Eliminate[] choke on simple systems

  • To: mathgroup at smc.vnet.net
  • Subject: [mg74740] Re: [mg74719] Solve[] and Eliminate[] choke on simple systems
  • From: anguzman at ing.uchile.cl
  • Date: Tue, 3 Apr 2007 00:27:25 -0400 (EDT)

Thanks. It was indeed a missing comma. The extra equation shouldn't
hurt (it was a direct reading of the Markov model).

On Apr 2, 2007, at 9:08 AM, anguzman at ing.uchile.cl wrote:

> Hello:
> I think there is comma missing at the end of equation 12. However,  
> it would imply 17 equations for 16 variables. I eliminated the  
> first  and Mathematica solve the system in a few seconds.
>
>
> Atte. Andres Guzman
>
>
>
>
>
>
> darrell.long at gmail.com ha escrito:
>
>> Hi,
>>
>> I am trying to convert some of my old stuff from another system  to 
>>  Mathematica.
>> Below is an example of a Markov model that takes the other system  
>> a couple of
>> seconds to solve, but Mathematica chews on forever (I gave up after
>> about 30 minutes).
>>
>> Since I'm a Mathematica newbie, perhaps there is some limitation I am
>> not aware of?
>>
>> eqns = {3*L*P333 == U*(P323 + P322 + P223 + P221 + P120),
>> (K + 2*L + U)*P323 == 3*L*P333,
>> (K + 2*U + L)*P313 == 2*L*P323,
>> (2*L + U)*P322 == 2*U*P312,
>> (2*U + L)*P312 == 2*L*P322 + 3*U*P302,
>> 3*U*P302 == L*P312 + L*P313,
>> (2*L + U)*P223 == U*(2*P213 + P212) + 2*U*P313 + U*(2*P113 + P111) +
>> K*P323,
>> (K + 2*U + L)*P213 == 2*L*P223,
>> (2*U + L)*P212 == L*P221 + 2*U*P202,
>> 3*U*P202 == L*(P213 + P212 + P211),
>> (2*L + U)*P221 == U*(P212 + 2*P211),
>> (2*U + L)*P211 == L*P221 + U*P202
>> (L + 2*U)*P113 == K*P313 + K*P213 + U*P102,
>> 3*U*P102 == L*P113 + L*P111,
>> (2*U + L)*P111 == 2*U*P102 + 2*L*P120,
>> (2*L + U)*P120 == U*P111,
>> P333 + P323 + P313 + P322 +
>>         P312 + P302 + P223 + P213 + P212 + P202 + P221 + P211 +  P113 +
>> P102 +
>>         P111 + P120 == 1}
>> vars = {P333, P323, P313, P322, P312, P302, P223, P213, P212, P202,
>> P221,
>>     P211, P113, P102, P111, P120}
>>
>> A = Solve[eqns, vars]
>>
>>
>>
>
>
>
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