Re: FindRoot and Derivatives

*To*: mathgroup at smc.vnet.net*Subject*: [mg24470] Re: FindRoot and Derivatives*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Wed, 19 Jul 2000 01:21:47 -0400 (EDT)*Organization*: Universitaet Leipzig*References*: <8l0rro$ecg@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi, you have to solve a differential equation -- FindRoot[] is for algebraic ones. DSolve[] and NDSolve[] may be helpfull. Regards Jens Chimba Mkandawire wrote: > > I'm running Mathematica 4.0 on a P3, 550Mhz Zeon, and I'm having problems. > Can FindRoot handle equations with derivatives? I've got this funky equation > with a first derivative, but I cannot get a solution. Here's my code. > > In[1]:= eq = g/(j*h)*y'[t]*Log[y[t]/h+1] + y[t]+a== > g*v + a*Exp[b*v*t]/(y[t]/h+1)^(b/d) > > In[2]:= n=0;v=1.;a=544.644;b=.000001;h=.6465;j=3.14094;g=182.965 > t=.1;n=0 > > In[3]:= FindRoot[n++;eq,{y,0.01,1}] > > and this is the error I get > > FindRoot::frnum: > Function (-182.955 + 1.38688 (0.&) is not a length 1 list of numbers at y = > 0.01'