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Re: NDSolve problem

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  • Subject: [mg86604] Re: NDSolve problem
  • From: dh <dh at>
  • Date: Fri, 14 Mar 2008 04:19:41 -0500 (EST)
  • References: <frclra$rom$>

Hi Payal,

your syntax is all wrong. What you have written are algebraic, not 

differential equations. Should dtPro[t] mean D[Pro[t],t]???

Further, your restrictions allows to eliminate one of the functions, 

what makes the problem easier. However you must first clarify if the 

restriction is compatibel with your equations (you mention that it is 

not:"I am unable to keep that condition under the currect setup that I 

have."). If it is not, then your equations are wrong.

hope this helps, Daniel

Payal Sheth wrote:

> Hello everyone,


> I am trying to simulate a chemical reaction to be solved using simulataneous differential equation shown below


> ndsolutioncombined0=NDSolve[{dtProCat[t]=8A-kcat*ProCat[t],

> dtPro[t]==kcat*ProCat[t],

> dtCat[t]==kcat*ProCat[t],

> dtProCatCompd[t]==k1*(ProCat[t]*Compd[t])-k2*ProCatCompd[t],

> dtCompd==k2*ProCatCompd[t]-k1*(ProCat[t]*Compd[t]),

> ProCat[0]=8A10,Pro[0]==0, Cat[0]==0, Compd[0]==0, ProCatCompd[0=

> ]==0},{Pro,Cat,ProCatCompd,Compd, ProCat}, {t,0,10000}, MaxSteps=AE 100000]


> To this, I would like to add a restriction Pro[t]+ProCat[t]+ProCatCompd[t]=10.


> Basically, at t=0, the reactant is ProCat=10, which as the reaction progresses with time is broken down into different products. However, the total reactant+product concentration shouldn't exceed the initial reactant concentration. I am unable to keep that condition under the currect setup that I have. For example, at different Compd concentration, at certain time points I have >10 of Prot+ProCat+ProCatCompd


> Can anyone tell me how I could add the restriction to my differential equations?


> Thanks,

> PS



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