*To*: mathgroup@smc.vnet.net*Subject*: [mg11153] RE: [mg11085] Differential Equation evaluation*From*: jmt <jmthomas@cybercable.tm.fr>*Date*: Mon, 23 Feb 1998 21:41:11 -0500*Organization*: TeA

Your equation seems to lead to a solution that in many cases tends to infinity at the infinity, so it is very unlikely you can set a condition like f'[Infinity]==0 2 eq = ((f')')'[x] + f[x] f'[x] + 1 - f'[x] == 0 DSolve[eq, f, x] bc0 = f[0] == 1 && f'[0] == 1 && (f')'[0] == 1 sol = NDSolve[eq && bc0, f, {x, 0, 30}, MaxSteps -> 100000] g = f /. sol[[1,1]] Plot[g[u], {u, 0, 30}] Hope this helps, ----------------------------------------------- Jean-Marie THOMAS Conseil et Audit en Ingenierie de Calcul www.cybercable.tm.fr/~jmthomas ------------------------------------------------ -----Message d'origine----- De: Spooky [SMTP:SLKBC@cc.usu.edu] Date: dimanche 22 fevrier 1998 20:55 A: mathgroup@smc.vnet.net Objet: [mg11085] Differential Equation evaluation Hi, I am new to Mathematica and just bought verison 3.0, I am trying to solve a differential equation of the form: F''' + F*F' + 1 - (F')^2 == 0 with boundry conditions for F, F', F'' at 0 and F' at infinity, is there a way to handle this? When I try this, if I include that boundry condition at infinity with the others, Mathematica tells me I have to many constraints, if I leave it off I can solve it, if I leave off the condition for F' at 0, it tells me it can't find the value of variable at the variable at 0. So, my question, is how do I handle this in Mathematica. I have another general question about the system. I am using version 3.0 for Win95. Often, if I make a syntax error, Mathematica will print me an error message but then I can't be certain that any subsequent error messages are valid. The reason I say this is that I will find my error, correct it and then I will get another error message upon evaluation. After struggling with it for a while, I will close it and re-enter and what gave me errors prior to re-entering, evaluate fine. Is there some way to be sure that the errors are valid? Thanks for all of your help. Shayne C. Rich SLKBC@cc.usu.edu