Services & ResourcesWolfram ForumsMathGroup Archive

[Date Index] [Thread Index] [Author Index]

Re: NDSolve Mathematica 6 and 7

• To: mathgroup at smc.vnet.net
• Subject: [mg103355] Re: [mg103336] NDSolve Mathematica 6 and 7
• From: Mark Perrin <m.perrin at me.com>
• Date: Thu, 17 Sep 2009 06:20:04 -0400 (EDT)
• References: <200909160946.FAA12985@smc.vnet.net>

Well it is a system of partial differential equations describing a  
wave of electrical depolarisation passing through a cable.

EQN1 := D[V[t, x],
     t] == -1/
      1 (iK1 + iKr + iKs + iNa + ibCa + ibNa + ipCa + iCaL + ipK +
       iNaCa + iNaK + istim[t, x] + ito);

EQN2 := D[Xs[t, x], t] == 2.57 ((xas - Xs[t, x])/tauxs);

EQN3 := D[s[t, x], t] == (sinf - s[t, x])/taus;

etc.

I can post the notebook here:

http://dl.getdropbox.com/u/127753/cablenotebook.nb

Other details:
	- running Mathematica 6 and 7 (depending on need)
	- Mac 10.6 Snow Leopard - but tested also on a windows computer  
running Mathematica 6 and 7 - same issue
	

Regards,

Mark P

On 17/09/2009, at 12:58 AM, DrMajorBob wrote:

> Send details, Mark. Details.
>
> Bobby
>
> On Wed, 16 Sep 2009 04:46:29 -0500, Mark Perrin <m.perrin at me.com>  
> wrote:
>
>> I was wondering if anyone could help me. I am solving a set of  
>> partial
>> and ordinary differential equations in Mathematica 7. For the same  
>> set
>> of equations and same expression i.e.
>>
>> solution =
>>  NDSolve[EQNS, STATES, {t, 0, 500}, {x, 0, 1.6}, MaxStepSize -> {1,
>> 0.01},
>>   MaxSteps -> Infinity, AccuracyGoal -> 5, PrecisionGoal -> 5]
>>
>> where EQNS are the ODEs.
>>
>> Mathematica 6 solves this in < 5 minutes.
>> Mathematica 7 takes about 40-45 minutes.
>> for the same solution.
>>
>> Same hardware etc.
>>
>> Can anyone please tell me if it is possible to speed up the solution
>> in Mathematica 7. Why would the two be so different?
>>
>> Kind Regards,
>>
>> Patch
>>
>
>
> -- 
> DrMajorBob at yahoo.com

• References:
  • NDSolve Mathematica 6 and 7
    • From: Mark Perrin <m.perrin@me.com>