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MathGroup Archive 2000

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FindRoot and Derivatives

  • To: mathgroup at smc.vnet.net
  • Subject: [mg24444] FindRoot and Derivatives
  • From: "Chimba Mkandawire" <bluntme at u.washington.edu>
  • Date: Tue, 18 Jul 2000 00:58:45 -0400 (EDT)
  • Organization: University of Washington
  • Sender: owner-wri-mathgroup at wolfram.com

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'




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