Re: NDsolve question

*To*: mathgroup at smc.vnet.net*Subject*: [mg29141] Re: NDsolve question*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Wed, 30 May 2001 23:28:27 -0400 (EDT)*Organization*: Universitaet Leipzig*References*: <9f2gjo$881$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi, and Mathematica has case sensitive names ! and g2 != G2 So G1 = 0.97536; G2 = 0.95079; G3 = 0.92583; G4 = 0.90336; G5 = 0.87948; will work. Regards Jens Supriyo Sinha wrote: > > Hi, > > I'm relatively new to Mathematica, but I heard > that Mathematica is better at solving differential equations. Anyways, > I'm trying to solve a set of six coupled differential equations (each > equation is coupled to a maximum of two other equations). When I try to > evaluation, I get the following error message: > > NDSolve::ndnum: Differential equation does not evaluate to a number at Z = > 0.. > > The code I'm trying to run is the following: > > Betapump = 2.23038 > Beta1 = 2.0744 > Beta2 = 1.92669 > Beta3 = 1.78431 > Beta4 = 1.66273 > Beta5 = 1.54011 > g1 = 0.97536 > g2 = 0.95079 > g3 = 0.92583 > g4 = 0.90336 > g5 = 0.87948 > NDSolve[{Kp'[Z] == -1*K1[Z]*Kp[Z] - Betapump*Kp[Z],Kp[0] == 1,K1'[Z] == > G1*(K1[Z]*Kp[Z]-K1[Z]*K2[Z])-Beta1*K1[Z],K1[0] == (0.1)^12,K2'[Z] == > G2*(K2[Z]*K1[Z]-K2[Z]*K3[Z])-Beta2*K2[Z],K2[0] == (0.1)^12,K3'[Z] == > G3*(K3[Z]*K2[Z]-K3[Z]*K4[Z])-Beta3*K3[Z],K3[0] == (0.1)^12,K4'[Z] == > G4*(K4[Z]*K3[Z]-K4[Z]*K5[Z])-Beta4*K4[Z],K4[0] == (0.1)^12,K5'[Z] == > G5*(K5[Z]*K4[Z])-Beta5*K5[Z],K5[0] == (0.1)^12},{Kp[Z], K1[Z], K2[Z], > K3[Z], K4[Z], K5[Z]}, {Z, 0, 500}] > > All the equations are pretty similar. I would actually prefer to use > DSolve to get an equation, but I will settle for the interpolated solution > given by NDSolve and plot it. > > Any help would be GREATLY appreciated. > > Thanks, > Supriyo > supriyo at stanford.edu > > --------------------------------------------------------------------- > "The presence of an enthusiast makes me as cold as ice, while I think > I should become passionately excited if I had much to do with a dull > and phlegmatic person." > > - Gregory Aleksandrovich Pechorin > M. L. Lermontov's A Hero of Our Own Times > > "...the only consolation you have left is to whip yourself..." > > - F. Dostoyevsky's Notes From the Underground