Re: export differential equation solution obtained

*To*: mathgroup at smc.vnet.net*Subject*: [mg106346] Re: [mg106326] export differential equation solution obtained*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Sun, 10 Jan 2010 03:28:03 -0500 (EST)*Reply-to*: hanlonr at cox.net

In your first equation (after "=" is replaced by "=="), you used p[t] in both terms. I changed the second to n[t] sol3 = NDSolve[{ p'[t] == -0.0491*p[t] - 0.0089*n[t], n'[t] == 0.0491*p[t] + (0.0491 - 0.0089)*n[t], p[0] == 25000, n[0] == 0}, {p, n}, {t, 0, 100}][[1]]; Plot[Evaluate[n[t] + p[t] /. sol3], {t, 0, 100}] Generate an array of the data that you want data = Join[{{"t", "n[t]", "p[t]", "n[t] + p[t]"}}, Table[{t, n[t], p[t], n[t] + p[t]}, {t, 0, 100, 5}] /. sol3]; Export["newdata.csv", data]; Bob Hanlon ---- Yun Zhao <yun.m.zhao at gmail.com> wrote: ============= Hi everyone, I would like to know if there is a way to export differential equation solution obtained through Mathematica to microsoft excel. There are several data processing things that I want to know, that simply plotting the solution in Mathematica won't suffice. I have a system of differential equations like so: sol3=NDSolve[{p'[t]=-0.0491*p[t]-0.0089*p[t],n'[t]=0.0491*p[t]+(0.0491-0.0089)*n[t],p[0]=25000,n[0]=0},{p,n},{t,0,100}] When I plotted it in Mathematica using this code: Plot[Evaluate[{n[t]+p[t]}/.First[sol3]],{t,0,100}] I get a exponential increasing function plotting number vs. time. What I want is the values of both the time vector and number vector, and I want to copy and paste them into two columns in microsoft excel. I tried using: Export["newdata.dat", Evaluate[{n[t]+p[t]}/.First[sol3]] But this gives me a .dat file with the time and number vectors all scrambled up. My question is: (1) is there a better way to tell Mathematica what I want to export, because I don't think Evaluate[{n[t]+p[t]}/.First[sol3] is the correct term to convey what I want (2) How do I properly export differential equation solutions that I can graph but not display in Mathematica, to spreadsheets software like Microsoft Excel? Thank you all very much.