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MathGroup Archive 2003

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Re: Log Equation

  • To: mathgroup at smc.vnet.net
  • Subject: [mg44764] Re: Log Equation
  • From: "Curt Fischer" <crf3 at po.cwru.edu>
  • Date: Tue, 25 Nov 2003 00:45:32 -0500 (EST)
  • References: <bps4gf$9uj$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Your equation has a real solution only for x less than about -0.2 or so.  In
this range you could use FindRoot[].

In[1]:=
? FindRoot

In[2]:=
f[y_] :=
       x /. FindRoot[y == \(1 - x\)\/Log[x], {x,
         1 + $MachineEpsilon, \ 10\^6}]

In[3]:=
f[-2]

Out[3]=
3.51286

In[4]:=
f[-1]
Out[4]=
1.

In[5]:=
f[-7]
Out[5]=
22.9259

In[6]:=
\!\(f[\(-10\^4\)]\)
Out[6]=
116672.

-- 
Curt Fischer



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