NDsolve question

*To*: mathgroup at smc.vnet.net*Subject*: [mg29119] NDsolve question*From*: Supriyo Sinha <supriyo at stanford.edu>*Date*: Wed, 30 May 2001 05:50:33 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Hi, I'm relatively new to Mathematica (I normally use MATLAB), 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