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FindFit::eit Error Message in Mathematica

• To: mathgroup at smc.vnet.net
• Subject: [mg128616] FindFit::eit Error Message in Mathematica
• From: benz43 <sittichaisahachaiwatana at hotmail.com>
• Date: Sat, 10 Nov 2012 02:06:52 -0500 (EST)
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• Delivered-to: l-mathgroup@wolfram.com
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Hi! I'm trying to fit the curve with my data and I got an error message that I don't have a clue what to do next, plz help!
(I'm very new to Mathematica)


this is the equation which is quite complex
http://www.4shared.com/photo/ybdQBp4m/Equation.html?

Equation = ((1 - ((Log[(1 + (x1/RMS1))])/(Log[(1 + ((10^6)/
             RMS1))])))*(1/(Log[(Exp[1] + ((x1/a1)^n1))]))^m1)


this is my data

data = {{3, 0.99}, {4, 0.99}, {4, 0.53}, {6, 0.12}, {15, 0.12}, {21, 
   0.12}, {21, 0.12}, {34, 0.12}, {33, 0.12}, {96, 0.11}}


FindFit[data, {((1 - ((Log[(1 + (x1/RMS1))])/(Log[(1 + ((10^6)/
              RMS1))])))*(1/(Log[(Exp[1] + ((x1/a1)^n1))]))^m1), 
  RMS1 > 0, a1 > 0, n1 > 0, m1 > 0}, {RMS1, a1, n1, m1}, {x1}]


it gives me error message
FindFit::eit: The algorithm does not converge to the tolerance of 4.806217383937354`*^-6 in 500 iterations. The best estimated solution, with feasibility residual, KKT residual or complementary residual of {2.34477*10^-6,0.0000672552,7.34805*10^-7}, is returned. >>


{RMS1, a1, n1, m1} = {5001580, 3.99808, 6550.2, 0.233221}


How can i fix this error ? Thanks for any help !