Re: NDSolve
- To: mathgroup at smc.vnet.net
- Subject: [mg42904] Re: NDSolve
- From: "Kevin J. McCann" <kjm@KevinMcCann>
- Date: Sat, 2 Aug 2003 04:12:28 -0400 (EDT)
- References: <bgctse$9l9$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Are k1, k2, km1, km2,M specified? It is difficult to reproduce results without all the information. Kevin "Steffen" <nnnx at gmx.de> wrote in message news:bgctse$9l9$1 at smc.vnet.net... > Hi all, > unfortunately Mathematica is not able to solve the following: > > NDSolve[{ > > y1'[x] == -k1 y1[x] y2[x] + km1 y3[x], > > y2'[x] == -k1 y1[x] y2[x] + km1 y3[x], > > y3'[x] == k1 y1[x] y2[x] + km2 y4[x] M - (km1 + k2 M) y3[x], > > y4'[x] == -km2 M y4[x] + k2 M y3[x], > > y1[0] = 10^13, > > y2[0] = 10^16, > > y3[0] = 0, > > y4[0] = 0, > > } , {y1 , y2 , y3 , y4} , {x , 0 , 50 10^-6}] > > > > This is a differential equation system for a kinetical system ( y1 + y2 <=> > y3 , y3 <=> y4). Only y1 and y2 exsists in the beginning. The constants k1, > km1, k2, km2 and M are numbers and are defined above. > > Mathematica gives an error: " NDSolve::ndnef : The number of differential > equations (3) is not equal to the number of the initial conditions (1)." > > But I did gave him all the initial conditions, did´nt I? By the way there > are 4 eq. and 4 conditions. > > I am sorry for this probably easy prob. I looked in Mathematica Help, in > this forum and at Wolframs MathSource Webpage. I did not find anything for > helping me to solve this Prob. This means, that I am making a very stupid > mistake, but I do not know, which one. Can please anybody help me? > > Thanks a lot > > Steffen Nasterlack > > University of Karlsruhe > > Germany > > >