NDSolve problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg86569] NDSolve problem*From*: Payal Sheth <itsmepayal at hotmail.com>*Date*: Thu, 13 Mar 2008 20:53:45 -0500 (EST)

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