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MathGroup Archive 2005

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Re: Avoiding divide by zero error in NDSolve

  • To: mathgroup at smc.vnet.net
  • Subject: [mg62479] Re: Avoiding divide by zero error in NDSolve
  • From: "Chris Chiasson" <chris.chiasson at gmail.com>
  • Date: Fri, 25 Nov 2005 02:25:40 -0500 (EST)
  • References: <dm49jj$sul$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Pradeep,
I think the solution is a constant value.
I renamed some of your variables, namely k1 is k[1], k2[1 thru 5] are
k[2 thru 6], and M is m, but here is my code showing the solution:

k[1]=100
eqns[1]=And[m'[t]\[Equal]k[1],m[0]\[Equal]0]
solns[1]=DSolve[eqns[1],m,t]
k[i_Integer/;i\[GreaterEqual]2]=20
eqns[2][i_]=And[D[m[t]y[i][t],t]\[Equal]k[i],y[i][0]\[Equal]k[i]/k[1]]
solns[2][i_]=DSolve[eqns[2][i],y[i],t]

y[2][whatevertime]
%/.solns[2][2][[1]]
%/.solns[1][[1]]

Sorry for renaming your reaction rate constants and molarities,
--
http://chrischiasson.com/contact/chris_chiasson


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